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Flowering Plants: Structure and Industrial Products
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Flowering Plants

Flowering Plants Structure and Industrial Products

Aisha Saleem Khan Forman Christian College Lahore Pakistan

This edition first published 2017 © 2017 John Wiley & Sons Ltd All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions. The right of Dr Aisha Saleem Khan to be identified as the author(s) of this work has been asserted in accordance with law. Registered Offices John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, USA John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK Editorial Office The Atrium, Southern Gate, Chichester, West Sussex, PO19 8SQ, UK For details of our global editorial offices, customer services, and more information about Wiley products visit us at www.wiley.com. Wiley also publishes its books in a variety of electronic formats and by print‐on‐demand. Some content that appears in standard print versions of this book may not be available in other formats. Limit of Liability/Disclaimer of Warranty The publisher and the authors make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of fitness for a particular purpose. This work is sold with the understanding that the publisher is not engaged in rendering professional services. The advice and strategies contained herein may not be suitable for every situation. In view of ongoing research, equipment modifications, changes in governmental regulations, and the constant flow of information relating to the use of experimental reagents, equipment, and devices, the reader is urged to review and evaluate the information provided in the package insert or instructions for each chemical, piece of equipment, reagent, or device for, among other things, any changes in the instructions or indication of usage and for added warnings and precautions. The fact that an organization or website is referred to in this work as a citation and/or potential source of further information does not mean that the author or the publisher endorses the information the organization or website may provide or recommendations it may make. Further, readers should be aware that websites listed in this work may have changed or disappeared between when this works was written and when it is read. No warranty may be created or extended by any promotional statements for this work. Neither the publisher nor the author shall be liable for any damages arising herefrom. Library of Congress Cataloging‐in‐Publication Data Names: Khan, Aisha Saleem, author. Title: Flowering plants : structure and industrial products / Dr. Aisha Saleem Khan. Description: First edition. | Hoboken, NJ : John Wiley & Sons, Inc., 2017. | Includes bibliographical references and index. Identifiers: LCCN 2016051233 (print) | LCCN 2016052638 (ebook) | ISBN 9781119262770 (cloth) | ISBN 9781119262800 (pdf ) | ISBN 9781119262787 (epub) Subjects: LCSH: Angiosperms. | Angiosperms–Utilization. Classification: LCC QK495.A1 K43 2017 (print) | LCC QK495.A1 (ebook) | DDC 582.13–dc23 LC record available at https://lccn.loc.gov/2016051233 Cover image: Courtesy of the author Cover design: Wiley Set in 10/12pt Warnock by SPi Global, Pondicherry, India 10 9 8 7 6 5 4 3 2 1

Dedicated to my dear and loving father without his support I would not have been able to write this book

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Contents Preface  xv Acknowledgements  xvii 1

1.1

An Introduction to Flowering Plants: Monocots and Eudicots  1

An Introduction to Major Group of Angiosperms: Monocots, Eudicots and Basal Angiosperms  1 1.2 Plant Cell: Revisions and Few Updates  5 1.2.1 A Cellulosic Cell Wall is Crucial for all Plant Cells  7 1.2.2 Plant Plasma Membrane Allows Molecules to Enter Only Through Their Respective Channels  11 1.2.3 Mitochondria Convert Energy of Glucose in ATP and in Reducing Powers  13 1.2.4 Plant Vacuoles Store Water, Pigments and Compounds of Defensive Nature  14 1.2.5 Golgi Apparatus  15 1.2.6 Nucleus Encodes Genes Required for Enzymes Forming Products of Commercial Applications  15 1.2.7 Plastids are Sites of Sugar and Fragrance Formation  16 1.2.8 Tannosomes are Chloroplast‐Derived Organelles Which Contain Polymers of Tannins  17 1.2.9 Ribosomes  17 1.2.10 Endoplasmic Reticulum  17 1.2.11 Peroxisomes 18 1.2.12 Oleosomes 19 1.3 Intracellular and Extracellular Communications are Crucial for Cells’ Metabolic Demands  19 1.4 Future Perspectives  22 References  23 Further Reading  23 An Introduction to Angiosperm Natural Products  31 2.1 Introduction  31 2.2 Glucose Serves as a Precursor for Formation of Primary and Secondary Metabolites in Plants  32 2.3 Classification of Natural Products of Angiosperms  33

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Contents

2.3.1

Alkaloids Provide Defense Against Herbivory Due to Their Bitter Taste in Plant Organs  33 2.3.2 Flavonoids are Important Pollination Pigments and Increase Plants’ Demands in Floriculture  35 2.3.3 Glycosides are Sugar‐Containing Natural Products  37 2.3.4 Terpenoids Make Fragrances and are Used in Perfume and Cosmetic Products  39 2.4 Techniques for Isolation of Secondary Metabolites With Future Perspectives  44 References  46 Further Reading  47 3 Plant Tissues Organization of Angiosperms  53 3.1 Introduction to Plant Tissues  53 3.2 Diversity of Plant Cell  53 3.3 Parenchyma is the Main Ground Tissue of Plants  55 3.4 Collenchyma: Introduction and Distribution  55 3.5 Sclerenchyma is the Mechanical Tissue of Plants  57 3.5.1 Fibers Types in Plants  57 3.5.2 Commercially Important Fibers  57 3.5.3 Making of Fabrics From Corn Fibers  59 3.5.4 Diversity in Sclereids  59 3.6 Vascular Tissues: Xylem and Phloem  61 3.6.1 Xylem  61 3.6.2 Why is There a Need of Water Transport?  61 3.6.3 Leaf Morphology and Venation  62 3.6.4 Tracheary Elements  63 3.6.5 Why Tracheids and Vessels are Water‐Transporting Cells?  65 3.6.6 Significance of Lignification in Xylem  65 3.6.7 Genetic Modification of Lignin for Bioenergy Crops  65 3.6.8 Pits and Pit Membranes  66 3.6.9 Proteomic Analysis of Xylem Sap Provides Evidences of Proteins Translocation Through Xylem Sap  66 3.6.10 Water Channels in Plant Membranes  69 3.7 Phloem  69 3.7.1 Significance of Callose Deposition  69 3.7.2 Companion Cells  69 3.7.3 Evaluation of Phloem Sap Through Modern Techniques  71 3.8 Future Perspectives  72 References  72 Further Reading  73 4

4.1 4.2 4.2.1

Floral Cell Biology and Diversity in Floral Cells  77 Introduction to Angiosperms Flowers: Monocots and Eudicots  77 Morphological & Anatomical Characteristics of Eudicot Flowers  77 Sepals Morphology and Anatomy  79

Contents

4.2.2 Petals Morphology in Response to Their Pollinators  81 4.2.3 Epidermal Cell of Petals and Elaiophores  85 4.2.4 Anatomical Characteristics of Eudicot Petals  87 4.2.5 Morphological and Anatomic Features of Carpels  87 4.2.6 Ovule Anatomy  90 4.2.7 Stamens: Morphology and Anatomy  93 4.2.8 Vascular Supply to Stamens  94 4.2.9 Stamen Anatomy and Pollen Development  94 4.3 Morphology of Monocots Flowers  95 4.3.1 An Account of Economic Importance of Z. mays (Corn)  96 4.4 Channels and Transporters Within Floral Cells  98 4.5 Future Perspectives  102 References  102 Further Reading  103 Signaling During Sexual Reproduction in Angiosperms  107 5.1 Introduction  107 5.2 Angiosperms Show Diversity in Their Sporophytic and Gametophytic Generations  108 5.3 Angiosperms Spend Most Part of Their Lives as Sporophytes and Produce Gametophytes for a Shorter Period of Time  108 5.4 Septs From Pollination to Fertilization  111 5.4.1 Stigma of Angiosperms May be Dry or Wet  111 5.4.2 Pollen Landing on Stigma (Rehydration)  119 5.4.3 Style Anatomy and Types in Angiosperms  119 5.4.4 Growth of Pollen Tube  120 5.4.5 Physiological Activities Within Pollen Tube  123 5.4.6 Cysteine Rich Proteins (CRP) Facilitate Pollen and Pistil Interaction  124 5.4.7 Steps Involved in Fertilization  124 5.4.8 Sperm Cell in Angiosperms  127 5.4.9 Molecular Basis of Reproduction  127 5.4.10 Temperature Affects Pollination  127 5.5 Future Perspectives  128 References  128 Further Reading  129

5

6

6.1 6.2 6.3 6.4 6.5

Physiologically Active Metabolic Pathways in Floral Cells  135

Introduction to Floral Physiology  135 Glucose Fates in Floral Cells Differ According to Their Metabolic Demands  137 PPP Provides Floral Cells With Their Nucleotides and Important Pigments  141 ATP and NADPH Produced Through Photochemical Reactions Provide Energy for Sugar Formation in Stroma of Chloroplasts  143 Floral Photosynthesis Contributes to Sugar Requirements of Floral Whorls  145

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Contents

6.5.1

Presence of Stomata and Chloroplasts in Flowers Facilitate Sugar Formation  149 6.5.2 Sepals of Angiosperms have Developed Many Adaptations for Foliar Photosynthesis  150 6.5.3 Photosynthesis in Anthers is Required for Metabolic Demands of Developing Pollen Grains  150 6.5.4 Chloroplasts in Exocarp of Fruits are Modified and are Photosynthetic  151 6.6 Future Perspectives  155 References  155 Further Reading  156 7

7.1

Anthocyanins: Accumulation in Plants and Role in Industries  161

Anthocyanins Accumulation in Different Organs Is Indicative of Their Multiple Roles  161 7.2 Anthocyanidin Biosynthesis Takes Place in Cytosol of Cells, However, They are Accumulated in Vacuoles  162 7.3 Anthocyanins Exist in Modified Forms in Cells  165 7.4 Anthocyanins Transport to Vacuoles  168 7.5 Anthocyanins Role is Dependent Upon Their Location and Accumulation  168 7.5.1 Accumulation are Defensive Pigments in Vegetative Organs  168 7.5.2 Accumulation and Role in Leaves  171 7.5.3 Anthocyanins are Involved in Senescence of Leaves  174 7.5.4 Anthocyanins as Defensive Pigments Against Insects  175 7.5.5 Anthocyanins Protect Plants Against UV Light  176 7.5.6 Role in Scavenging Reactive Molecular O2  176 7.5.7 Anthocyanins are Crucial for Pollination and Seed Dispersal in many Eudicots  176 7.5.8 Accumulation in Fruits  178 7.6 Industrial Applications of Anthocyanins  178 7.7 Future Perspectives  181 References  182 Further Reading  184 8

8.1 8.2 8.3 8.4 8.5 8.6 8.7

Carotenoids: Introduction, Classification and Industrial Uses  189

Carotenoids are Vital for Leaves as Light Absorbing Pigments and for Flowers to Attract Their Pollinators  189 Oxygenated and De‐oxygenated Carotenoids are Major Carotenoids in Angiosperms  190 Carotenoid Biosynthesis is Under the Control of Transcriptional Regulation  193 Carotenoids are Localized in Plastids in Form of Crystals and Plastoglobuli  193 Carotenoids Accumulation Takes Place in Chromoplasts of Autumn Leaves of Eudicots  197 Carotenoids Pigments in Flowers and Pollens  197 Lutein are Important Antenna and Photoprotective Pigments in Thylakoids of Chloroplasts  199

Contents

8.8

Capsaicin is a Carotenoid Derivative Which Causes Hotness of Capsicum spp.  200 8.9 Carotenoid Accumulation in Epidermal Cells of Many Fruits is Due to Conversion of Chloroplast Into Chromoplasts  202 8.10 Transcriptional Regulation of Carotenoids in Fruits  203 8.11 Application in Food, Pharmaceutical, Cosmetic, Textile and Nutracuetical Industries  203 8.12 Future Challenges  205 References  207 Further Reading  208 9

9.1

Alkaloids Biosynthesis, Translocation and Industrial Products  213

Alkaloids are Nitrogen‐Containing Natural Products Which Provide Defense Against Herbivores  213 9.1.1 An Account of Historical Uses of Alkaloids  214 9.1.2 Many Alkaloids are Psychoactive Compounds and Act as Neurotransmitters  215 9.2 Alkaloids are Synthesized in Cytosol and Accumulated in Vacuoles as They are Toxic for Plant Cells  216 9.2.1 Monoterpenoids Indole Alkaloids (MIA) Derivatives are Synthesized From Tryptophan  216 9.2.2 Tropane Alkaloids are Tyrosine Derivatives  216 9.3 Purine Nucleotides Serve as Precursors of Caffeine Synthesis  219 9.4 History of Discovery of Caffeine  222 9.4.1 Caffeine is a Popular Stimulant Alkaloid in Coffee and Teas  223 9.4.2 Industrial Steps in Coffee Making Determines Their Aroma and Taste  223 9.4.3 Supercritical CO2 Method is Efficient for Producing Decaffeinated Coffee  224 9.4.4 Teas are Representative of Culture, Tradition and Civilization  224 9.4.5 Black, Green and Oolong Teas  226 9.5 Theobromine is an Alkaloid Widely Used in Chocolates and Teas  227 9.5.1 Chocolate Formation: From Cacao Beans to Markets  227 9.6 Clinical Applications of Alkaloids are Due to Their Mode of Action  228 9.7 Development of Physiologically Functional Food Containing Alkaloids as Food Vaccines  230 9.7.1 Development of Transgenic Caffeine Resistant Plants  230 9.7.2 Use of Caffeine in Cosmetic Products  231 9.7.3 Alkaloids in Medicinal Products  231 9.7.4 Future Challenges for Agriculture and Cosmetic Industries  235 References  236 Further Reading  237 10

Nectaries, Carnations and Ornamental Hybrid Flowers in Floriculture  241

10.1 Introduction  241 10.2 Nectaries are Nectar Synthesizing Structures of Plants  242 10.2.1 Nectar Guides  242 10.2.2 Nectar Secretion and Important Metabolites  243 10.2.3 Molecular Basis of Nectar Secretion  245

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Contents

10.3 Ornamental Transgenic Plants in Floriculture  247 10.3.1 Development of Transgenic Roses  247 10.3.2 Ornamental Hybrids in Floriculture  248 10.4 Dianthus spp. are Major Carnations in Floriculture  250 10.4.1 Economic Importance of Carnations  254 10.4.2 Genetically Modified Carnations and Ornamental Plants  254 10.5 Future Perspectives in Floriculture Industries  255 References  255 Further Reading  256 11

11.1

Floral Essential Oils: Biosynthesis, Classification and Commercial Applications  261

Fragrance Formation is a Unique and Genetically Controlled Characteristic of Many Angiosperms  261 11.2 Number of Carbon and Hydrogens Atoms in Isoprene Units Determine Their Roles in Plants  263 11.2.1 Two Isoprene Units (Monoterpenes) are Responsible for Giving Fragrances  263 11.2.2 Secretory Structures and Mechanisms Involved in Release of Essential Oils  264 11.2.3 Formation of Monoterpenoids Like Menthol is a Part of Chemical Defense of Mint and Other Plants  266 11.2.4 Linalool is a Defensive Terpenoid and a Volatile Attractant  266 11.2.5 Geraniol: A Volatile Attractant and Defensive Essential Oil in Cosmetic and Medicinal Products  270 11.3 Many Terpenoids are Insecticidal and Act as Allelochemicals  272 11.4 Sesquiterpenes are Defensive Terpenoids of Many Plants  272 11.5 Diterpenoids are Important Phytohormones Which Comprise of Four Isoprenoid Inits  274 11.6 Terpenoid Biosynthesis in Plants Proceeds in Two Different Cellular Compartments  276 11.6.1 Vanillin Biosynthesis  278 11.7 Economically Important Terpenoids  278 11.7.1 Bio‐engineered Terpenoids  281 11.8 Future Challenges  282 References  282 Further Reading  283 12

12.1 12.2 12.3 12.4

Aromatic Molecules From Flowers in Perfume and Cosmetic Industries  287

Introduction and Overview of Perfume and Cosmetic Industries  287 History of Perfume Making  288 Aromatic Flowers, Leaves and Woods Used in Perfumery  289 Traditional and Modern Techniques of Distillation and Isolation of Fragrant Molecules  290 12.4.1 Collection & Extraction of Essential Oils are Prerequisite Steps in Traditional Perfume Making  291 12.4.2 Enfleurage & Maceration Through Grease and Fats  291

Contents

12.4.3 Solvent Extraction Convert Aromatic Molecules in Concrete and Absolute  291 12.4.4 Eau De Parfum, Eau De Toilette and Eau De Cologne  294 12.4.5 Perfume Notes  294 12.5 CO2 as a Solvent to Extract Fragrant Molecules in Super‐critical CO2 Fluid Extraction Method  294 12.6 Modern Perfume Making Machines  296 12.7 Aromatherapy: Relaxation Through Aromatic Molecules  296 12.8 Cosmetic Industry: An Overview and History  298 12.9 Popular Plants and Their Products in Cosmetic Products  300 12.10 Anti‐Aging Properties of Some Plants and Their Applications in Cosmetic Products  301 12.11 Bioengineered Aromatic Bacteria With Lemon and Rose Fragrances  302 12.12 Future Considerations  307 References  307 Further Reading  308 Glossary  311 Index  321

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Preface My inspiration for writing a book on Applied Plant Biology came from many authors whose work has captivated my imagination, since I was an undergraduate student. I have been teaching Applied Plant Biology to undergraduate and postgraduate students for the last 12 years. It is not only my area of specialization but my passion as well. Being a botanist, I always felt the urge for a book which relates plant structure with their important functional products and commercial applications. I believe that angiosperms structure and their important products need to be discussed together in order to have a clear understanding of how the plant architect influences the formation of important products. The following book relates morphological aspects of flowering plants alongwith their products in different industries in a unique, informative, more conceptual and an interesting way with research‐based and updated knowledge. There is a strong need to c­orrelate flowers of angiosperms with their compounds of industrial importance as it is rare to find books which characterize and highlight important products of angiosperms from flowers, fruits and seeds alongwith their morphology. I am sure that with the n­ecessary topics covered, the following book can be introduced as a textbook for all students of plant biology as it will capture their interest towards plants biology. Students all over the world find the study of plants more or less difficult or dry, which does not always aspire their general interest. One of the reason behind this is that the general consensus amongst the academic scientific community has negated the plant sciences its real position due to other emerging trends in biological sciences. Consequently, s­ubjects characterized in the realm of fundamental sciences are loosing their inert value as one of the integral components in comprehending biology. Although this book is primarily designed for the students of plant sciences, it is also be helpful for researchers who are associated with the different industries, as it covers plants products of commercial value that are being used by food, agriculture, pharmaceutical, beverages, textile, dye, floriculture, perfume, and cosmetic industries. This book covers topics like making of bioengineered bacterial perfumes from roses, development of transgenic herbivores resistant plants, modern trends in developing ornamental medicinal plants, plant‐derived nutraceuticals, plant pigments as dye‐ sensitized cells and also the role of plant hormones as antiaging molecules. Various distillation methods and techniques like supercritical CO2 methods for extraction of essential oils, gas chromatographic and mass spectrometric techniques are also included. Life cycles of plants and evolutionary relationships in molecular phylogenetics are included with future perspectives to develop student’s interests in plant biology.

xvi

Preface

It also explains diversity in floral cells which relate their metabolic activities, how cells of sepals differ from petals, ovary and stamens, and how they manage carbohydrates to fulfill their energy demands? In addition, it also covers the formation of important products within floral cells, intercellular and intracellular communications and different steps which are involved in making them commercial; molecular aspects of pollination, pigmentation and reproduction events in angiosperms are also discussed.

xvii

Acknowledgements I am thankful to my dear students who motivated me and suggested me to write a book on the following subject. I am extremely thankful to Sara Dar, designer, for drawing computer illustrations of this book. I am also thankful to Dr. Samina Mehnaz, my c­hairperson for motivating me throughout writing of this book and also to my c­olleagues Dr. Aafia Aslam and Dr. Asma Maqbool. My sincere thanks are to my family members, my siblings and my dear friends. I am also thankful to John Wiley & Sons for giving me this opportunity and for m­aking my dream come true.

1

1 An Introduction to Flowering Plants: Monocots and Eudicots There is no doubt about it that plants are main producers of ecosystem and important in every aspect of our daily lives. Many products which are used in food, nutraceutical, pharmaceutical, textile, cosmetics, perfumery, coffee, tea and beverage industries are in fact derived from plants. They are biosynthesized in different parts of plants and are known as natural products or secondary metabolites. Many of these compounds are defensive in nature which are produced during primary metabolic activities in plants. Many pigments in flowering plants are also secondary metabolites which are crucial for their pollination. Secondary metabolites include alkaloids, flavonoids, betalains, glyco­ sides, tannins, terpenoids and saponins. They will be introduced in the next chapter. This book deals with flowering plants, that is, angiosperms as they make one of the abundant group of plants of economic importance. However, before discussing major products of angiosperms, their biosynthesis and applications, it is important to discuss what are angiosperms? How did they evolve? What is their body organization and what kind of cells they have? So in the next section, a brief introduction of angiosperms and their classification is discussed.

1.1  An Introduction to Major Group of Angiosperms: Monocots, Eudicots and Basal Angiosperms All plants are considered to be a group of related organisms which are capable to ­synthesize their own sugars during photosynthesis, possess the cell wall, and generally with the differentiation of their bodies in roots, stems, leaves, flowers or flower‐ like structures. But recent trends in molecular phylogenetics have shown that they are not as much closely related as thought before. In fact, plants can be best described as ‘a group of different organisms which evolved independently during course of evolution and share similar characteristics like ability to synthesize their own food within their chloroplasts, have chlorophyll a as a necessary photosynthetic pigment and possess the cell wall which largely comprises of cellulose’. Their body is differentiated in vegetative and reproductive organs (spore or seed‐producing structures) and are therefore ­classified in one kingdom plantae. Division within kingdom plantae is based either on the presence or absence of vascular tissues (xylem and phloem) or spore‐producing structures.  Bryophytes like liverworts, hornworts and mosses are non‐vascular spore producing plants while pteridophytes are vascular plants which produce spore, for Flowering Plants: Structure and Industrial Products, First Edition. Aisha Saleem Khan. © 2017 John Wiley & Sons Ltd. Published 2017 by John Wiley & Sons Ltd.

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Flowering Plants: Structure and Industrial Products

example, ferns, horsetails and clubmossses. Other two major groups are seed‐producing plants, that is, gymnosperms which produce seeds which are not enclosed within their ovaries, and angiosperms or flowering plants, in which seeds develop within carpels and are covered by ovary wall. Angiosperms also known as flowering plants are the largest monophyletic group of seed producing plants which have evolved many efficient ways of survival over the period of time. They are unique from other group of plants due to the development of endosperm (nutritive tissue around embryo within seeds), flowers with carpels and ­stamens having two pairs of pollen sacs and phloem for transportation of sugars. Their fossils are over 135 million years old. Angiosperms are considered to be close relatives of living gymnosperms but some recent evidence suggested that seed ferns represent sister group to angiosperms. They are relatively evolved group of plants as compared with gymnosperms as they possess several mechanisms which ensure successful asexual and sexual reproduction, one of the main reason which makes them one of the abun­ dant group of seed plants. Although monocots (angiosperms with one cotyledons) and dicots (angiosperms with two cotyledons) are referred as two main groups of angiosperms but modern classifica­ tion which is based on molecular evidences have characterized angiosperms as core and basal angiosperms according to their monophyletic origin (descendants of common ancestors) and facts provided by molecular data including studies from DNA sequences from chloroplasts gene rbcL. Therefore, modern system of plant taxonomy, that is, Angiosperms Phylogeny Group (APG) system is a molecular‐based systematics which retains order and families of Linnean systems and includes groups which are monophy­ letic. APG I was published in 1998 which was followed by APG II in 2003 (Chase et al., 2003) and APG III in 2009 (Bremer et al., 2009) and then APG IV in 2016. However, further development in molecular techniques, advancement in techniques related to metabolomics and proteomics is exploring the molecular phylogenetics which will form foundation of evidence‐based classification of flowering plants. Evolutionary evidences suggest that basal angiosperms which are characterized by absence of xylem vessels are primitive, however, some recent phylogenetic analysis reported that Amborella trichopoda is sister to all extant angiosperms and is at the base of angiosperms phylogenetic tree. They are composed of only few species which include many aquatic plants like water lilies (Figure 1.1), Amborella and star anise. Core angio­ sperms are represented by monocots and core eudicots. They include three major groups including monocots, eudicots and magnoliids, and the latter group was once considered to be dicots but now it is placed in a separate group. Important magnoliids include plants like avocado, black pepper, magnolia, nut‐meg, bay leaf, tuliptree or yellow poplar. Eudicots also known as true dicots, composed of more than 75% of angiosperms and are characterized by their monophyletic origin and presence of tricolpate pollens (­having three apertures). This group of angiosperms represents abundant clade of angiosperms. Figure 1.2 shows a cladogram of flowering plants based on information from APG I, II and III. A cladogram represents an evolutionary diagram which is used to explain evolutionary relationships within a group of related organisms which share common ancestors. Orders of basal angiosperms (Amborellales, Nymphaeales and Austrobaileyales) represent primitive groups whereas core eudicots are represented as advanced or modern group of flowering plants. Magnoliids like Laureales, Magnoliales, Canellales and Piperales are evolved with monocots. Eudicots represent abundant group of flowering plants, among which core eudicots include two highly evolved and

An Introduction to Flowering Plants: Monocots and Eudicots

Figure 1.1  (a‐b) Basal angiosperms, (a) Nymphaea alba from family Nymphaeaceae, (b) Magnolia sp. is another basal angiosperm which belongs to family Magnoliaceae.

(a)

(b)

diverse clades which evolved separately are asterids (lamiids and campanulids) and rosids (fabids and malvids) (based on APG III) which are classified on the basis of their tendency to produce fused or free petals (Figures 1.3 and 1.4). Evolutionary traits, apo­ morphies, which are important in classification are represented where the origin of a clade takes place. Eudicots represent group of many economically important plants like members of family Apiaceae, Asteraceae, Brassicaceae, Cucurbitaceae, Fabaceae, Malvaceae, Rosaceae and Solanaceae. Other main group of flowering plants, that is, monocots represent one of the highly evolved clade with monophyletic origin (Figure 1.5). They are characterized by presence of only one cotyledon, non‐woody stem, fibrous roots, long and slender leaves with par­ allel venation and scattered vascular bundles. They produce inconspicuous, mostly non‐ fragrant flowers with floral parts in multiple of three often which are arranged to form a spikelet in case of grasses. Table  1.1 shows comparison of monocots and eudicots. Commelinid clade represents most derived group of angiosperms which includes many plants from Arecales, Commelinales, Poales and Zingiberales. Monocots include palms, orchids and grasses which evolved about 60 millions years ago and are composed of almost 10,000 species. Fossils of palms and members from arum family are the oldest known monocots which are reported to found in rocks almost 100 millions years old. Monocots include many economically important plants which make our staple food like all cereals and grasses are monocots. They are important source of biofuel and bioenergy.

3

Angiosperms (flowering plants)

Basal angiosperms

Core eudicots (75% flowering plants)

Monocots (25%)

Magnoliids

Rosids

Asterids

ids mi La es al yll ph s ryo alale Ca nt Sa ds

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lid

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Pi

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oty oc

es tal Vi s ale rag xif es Sa nal lle Di ales er nn les Gu ndrales de xa s ho u le oc Babia es Tr S eal ot Pr les ula nc nu Ra les lla hy op rat ns

on

Ce

M

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Free petals

es

les lla es ne ial Ca nol ag M

s ale ur La eae c ha nt es ra al lo ley s Ch bai ale tro ae es us ph l A ym ella N bor m A

(Daisy)

Fused petals (Brassica)

(Grass flower)

Flower in multiple of 3 Pollen monocolpate No vascular cambium Scattered vascular bundles Parallel venation

Vascular bundles

vascular bundles

Tricolpate pollen Vascular cambium present, vascular bundles not scattered Reticulate venation

Seed with one cotyledon

Sieve tubes with companion cells for conducting carbohydrates Ovules with 2 integuments Presence of endosperm in ovule Male gametophyte with 3 nuclei Stamen with 2 lacteral theca Female gametophyte with 8 nuclei Carpels

Companion cell Phloem (as seive tube member)

Flowers

Figure 1.2  A cladogram of angiosperms based on information from the Angiosperms Phylogeny Group (APG III, 2009) (Bremer et al., 2009).

An Introduction to Flowering Plants: Monocots and Eudicots

(a)

(b)

(c)

(d)

(e)

Figure 1.3  (a‐e) Rosids (fabids and malvids) are characterized by the presence of free petals (a) Quisqualis indica, (b) Chamelaucium uncinatum, (c) Millettia peguensis is an economically important plant with insecticidal properties and antiviral activities, (d) Tropaleum majus is an ornamental member of family Tropaeolaceae, and (e) Rosa sp. which belongs to Rosaceae is one of the popular ornamental and medicinal shrub.

Before describing the functional products of angiosperms, their biosynthesis and industrial uses, it is important to revise and update knowledge about angiosperms cell. So the following section will be dealing with the structure of an angiosperm cell along with some updates.

1.2  Plant Cell: Revisions and Few Updates All plant cells are surrounded by the cell wall which not only protects them but also gives them definite shape. A lipoprotein bilayer, that is, plasma membrane is present next to the cell wall and regulates the movement of molecules in and out of plant cells.

5

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Flowering Plants: Structure and Industrial Products

(a)

(b)

(c)

(d)

Figure 1.4  (a‐d) Asterids (lamiids and campanulids) are core eudicots which are differentiated from other eudicots due to the presence of fused petals (a) Petunia hybrid, (b) Daisy, (c) Lycopersicon esculentum, (d) Duranta erecta.

(a)

Figure 1.5  (a‐e) Monocots are composed of many economically important plants: (a) Wheat (Triticum aestivum) is a major cereal, bioenergy crop and a staple food worldwide.

An Introduction to Flowering Plants: Monocots and Eudicots

(b)

(c)

(d)

(e)

Figure 1.5 (Cont’d)  (b) Arum lily (Zentedeschia aethiopica) showing spadix (in yellow) and spathe, (c) Epipremnum aureum is a popular house plant which removes many indoor pollutants, such as formaldehyde, xylene and benzene, (d) Bambusa sp., (e) Canna indica also known as canna lily is used in constructed wetland for the removal of organic pollutants and heavy metals.

Plasma membrane encloses many membrane‐bound structures, that is, organelles which are present within a fluid cytosol which is the site for main metabolic activities of cell. Main organelles which are part of almost every plant cell include nucleus, ­mitochondria, plastids, vacuoles, endoplasmic reticulum, Golgi apparatus and ribosomes. However, in addition to this, plant cell may also contain microbodies, tannosomes, anthocyanoplasts and oil bodies depending upon their physiological role (Figure 1.6). 1.2.1  A Cellulosic Cell Wall is Crucial for all Plant Cells

Angiosperms show diversity in chemical composition of their cell wall which is the outermost covering of every plant cell whether it is a cell of root, leaf, stem, flower, fruit or seed. Each cell of these organs possess their own cell wall which gives them rigidity, support and a definite shape along with cytoskeleton which is composed of a network of microtubules and actin filaments. Cytoskeleton is involved in orientation of cellulose

7

Table 1.1  A comparison of two major group of core angiosperms. Characteristics

Monocots

Eudicots

Root

Fibrous, vascular bundles are collateral

Taproot, xylem in centre

Stem

Soft, herbaceous with scattered vascular bundles

Soft in non‐woody herbs or woody but vascular bundles are compactly arranged

Wheat (Triticum aestivum)

Coriander (Coriandrum sativum)

Leaf

Parallel venation

Reticulate venation

Flower

Ear of wheat

Umbel inflorescence of coriander

Fruit

Wheat hull or husk

Coriander fruit

Seed

Wheat grains (monocots)

Seeds showing two cotyledons (eudicots)

Pollination

Mostly wind pollinated

Pollination through insects and animals

Pollen grains

Monocolpate

Tricolpate

(c)

(b) (a)

Oleosomes

Plasmodesmata

Peroxisome Golgi body Nuclear membrane

Storage vacoule Crystals

Ribosomes Nucleolus

Palisade cell of leaf

Smooth endoplasmic reticulum Rough endoplasmic reticulum

Tannosome

(d)

Seed cell

(e)

Cell wall

Chromatin

Chloroplast

Plasma membrane

Anthocyanoplasts Mitochondrion

Lytic vacoules

Eudicot petal cell

Monocot floral cell

Figure 1.6  (a‐e) Plant cells show differences depending upon their role: (a) A typical plant cell, (b) Cells of mesophyll of leaves contain abundant chloroplasts due to their role in photosynthesis, (c) Seed cells of many plants store lipid in form of oil bodies or oleosomes, (d) Cells of petals of many eudicots contain large vacuoles for storing water soluble pigments in order to attract their pollinators, (e) Vacuoles of sepals and petals (perianth) of most monocots are not as conspicuous as in eudicots, as many of them are pollinated by wind. (See insert for color representation of the figure.)

10

Flowering Plants: Structure and Industrial Products

microfibrils and organizes the plane of cell division. Cellulose exists in the form of ­crystals in the cell wall and forms microfibrils which are embedded within the cell wall. The cell wall is also crucial for cell growth and development. Structural and chemical differences in the cell wall may exist within a tissue or and even within a cell. The cell wall of roots epidermal cells may be different from the cell wall of epidermal cell of stem, leaf or flower depending upon its physiological role. Primary cell wall is characteristic of all plants cells and is composed largely of cellu­ lose microfibrils which are embedded in a matrix of pectin and cross‐linking glycans. The matrix of the cell wall is laid down in cell plate followed by synthesis of cellulose microfibrils after the plate has reached the side of cells. However, secondary cell wall is characteristic of xylem tracheary elements and fibers and involves deposition of lignin, a phenolic compound. Primary cell wall is composed of almost 35% of cellulose, 35% pectin and 25% hemi­ celluloses compounds. Cellulose is the main carbohydrate of cell wall which exists as unbranched polymer of D‐glucose molecules connected by ß‐1,4 glycosidic linkage. Major hemicelluloses (branched polymer) of the cell wall are xylans, glucomannans, xyloglucans and ß‐D‐glucans. The protein part of the cell wall includes cyclins and expansins which are important for growth and development of the cell wall. Pectin compounds are important constituents of the cell wall which are present in middle lamella which is the outer cementing layer of the cell wall. Galactouronic acids connected by α‐1,4‐D are basic units of pectins. Incorporation of methyl groups to ­carboxylic groups of these units make them esterified. Their linkage with Ca++ and Mg++ makes pectic compounds insoluble, thus, limiting cell wall application in food industry. Pectic compounds like galactouronic acids, rhamnogalactouronins (RGI and II) prevent the cell wall from dehydrating, give them shape and cause expansion. However, RGII in primary cell walls exists in form of dimer cross‐linked with borate. This dimer provides enough support to the cell wall for its growth. Secondary cell wall is different from primary cell wall in having more cellulose and due to the presence of lignin. Both are attached with each other by means of covalent bonding. In addition, secondary cell wall is composed of hemicellulose and lignin which is deposited between plasma membrane and primary wall and prevents enlargement of the cell. Precursors of secondary wall synthesis like monolignols are secreted into the cell wall space and become randomly cross‐linked depending upon reactive oxygen spe­ cies, generated by laccases and peroxidases which makes the cell wall resistant against pathogens and also gives structural support to the cell wall. Some alcohols like coniferyl, caumaryl and sinaply groups are also part of secondary cell wall along with deposition of lignin. Monocots are different from eudicots in many ways. Some differences also exist in the cell wall, that is, presence of different polymers type and their abundance in the cell wall, presence of SiO2 forming phytoliths, especially cell walls of commeliinids includ­ ing grasses contain relatively small amount of pectin and structural proteins. The cell walls of monocots are composed of upto 30% cellulose, 25% hemicelluloses, 30% pectin and up to 10% glycoproteins with an increased amount of ferulate in plants like wheat, maize, rice and sugarcane which are linked with glucurunoarabinoxylans (GAX) (Molinari et al., 2013). Furthermore, a unique feature of the cell walls of grasses includes accumulation of β‐glucan in addition to GAX during their elongation.

An Introduction to Flowering Plants: Monocots and Eudicots

Presence of gelatin‐like properties of the cell wall which is due to O‐acetylated of the cell wall polymers, increases its applications in food industry. However, their presence also limits their use in biofuel technology and modern research is focusing on reduction of O‐acetylation of plants’ cell wall (Gille & Pauley, 2012). In the cell walls of dicots, only side chains of galactosyl‐residue in xyloglucans are O‐acetylated, however, in mono­ cots‐like grasses glucosly‐residues of xyloglucans are O‐acetylated. Recent emerging trends in cell wall technology include determination, modification and isolation of cell wall polymers for use in biomaterial, pharmaceutical and food industries through techniques like NMR and mass spectrometry. Orientation of ­cellulose fiber in the cell wall can be determined through Raman micro spectroscopic methods in herbaceous plants (Sun et al., 2016). Recently, cotton fibre is considered to be a single‐cell model for cell wall and cellulose research. The cell wall not only provides protection to the cell but also provides passages for the entry and exit of molecules in the form of pores, known as plasmodesmata which are extensions of smooth endoplasmic reticulum and regulate transport of molecules within range of 900 daltons. A typical plant cell may have more than 10,000 plasmodes­ mata on all sides of the cell wall, the exception being the outer side of epidermal cells. Plasmodesmata provide connections among cells for the transport of molecules, ­however, transport through plasmodesmata is not specific like cell membrane. There may be up to 1,000 to 10,000 or even more number of plasmodesmata present within a single plant cell. Plasmodesmata are of two kinds, primary and secondary. Primary ­plasmodesmata are formed during cell division. They are extensions of smooth endo­ plasmic reticulum in the form of tube, that is, desmotubules which are lined with plasma membrane through filamentous proteins (Figure  1.7). Secondary plasmodesmata are branched which develop during cell expansion. Plasmodesmata play important role ­during floral development and also involved in intercellular signaling especially in ovules. 1.2.2  Plant Plasma Membrane Allows Molecules to Enter Only Through Their Respective Channels

Plasma membrane is the lipid and protein part of a plant cell next to the cell wall which regulates the transport of molecules. The lipid part of membrane makes a bilayer of phospholipids which provides a barrier for transport of molecules due to its hydropho­ bicity. Significance of bilayer is to give support to many protein channels which are embedded within plasma membrane, and also for better trapping of molecules inside the cytosol. Non‐lipid part of plasma membrane is composed of proteins which makes up to 75% of membrane and allows transport of molecules which cannot simply cross the membrane through diffusion. They include polar and large molecules like sugars or charged molecules like amino acids, nitrates, sodium, potassium, calcium, and so on. Concept of plasma membrane is just like a room, whereas proteins make the gates, where molecules will cross their respective gates or channels (Figure 1.8). Plasma mem­ brane also regulates the movement of water molecules through aquaporins channels. Water molecules pass in a single row through this pore. Although plasma membrane is the main membrane of cell, but organelles like ­mitochondria, chloroplasts, nucleus, vacuoles also have their own lipids bilayers which perform role of plasma membrane. Plant membranes also are composed of several

11

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Flowering Plants: Structure and Industrial Products

(a)

Middle lamella

Primary plasmodesmata Plasma membrane

Secondary plasmodesmata

Cell wall

(c)

(b)

Flimentous protein

Middle lamella Desmotubule Central rod

Flimentous protein Central rod on desmotubules Plasma membrane

Cell wall Plasma membrane Smooth ER

(d)

Figure 1.7  (a‐d) (a) Plasmodesmata are extensions of smooth endoplasmic reticulum (SER) and main connections within the cell wall which allow transfer of water and other molecules from one cell to other, (b) Detailed structure of plasmodesmata showing desmotubule which extends from one cell to next through smooth ER, (c) Cross section of a desmotubule, (d) A view of plasmodesmata view within plant cell.

An Introduction to Flowering Plants: Monocots and Eudicots

Plasma membrane Protein channels on plasma membrane (top view) Apoplast

Plasmodesmata Cell wall

Figure 1.8  Plasma membrane of plant cells is enclosed in the cell wall which surrounds it from all sides (top view). Round circles on plasma membrane represent proteins which provide passage for regulation through plasma membrane. Gaps in the cell wall indicate plasmodesmata.

s­terols, for example, sitosterols, stigmasterol being the most abundant one. However, membrane sterol composition is dependent upon ecophysiological conditions involved in growth and development. 1.2.3  Mitochondria Convert Energy of Glucose in ATP and in Reducing Powers

Mitochondria are the site of cellular respiration and synthesize energy in the form of ATP for various metabolic needs of cells. Mitochondria multiply by division and are maternally inherited. Mitochondria have two membranes, outer and inner which are made up of phospho­ lipid bilayers. However, outer membrane of mitochondria comprises mostly lipids, whereas the inner membrane contains almost equal amount of lipids as well as proteins. The inner membrane is folded to increase surface area for metabolic processes like the electron transport chain and these invaginations are known as cristae. Outer m ­ embrane of mitochondria have proteins, that is, porins through which they communicate with the cytosol of cell and allow transfer of molecule upto 10KD, such as glucose and many ions. However, inner membrane is more permeable to molecules like CO2, H2O having pores for transport of molecules like ATP, ADP and pyruvate. Many proteins which are required for metabolic activities of mitochondria are carried through binding with receptor in an energy‐dependent transport. Space between two membranes is inter membrane space and fluid part of mitochon­ drion within cristae is known as mitochondrial matrix which is site of many processes that are crucial for providing energy to the cell. Products from glucose breakdown are transported to mitochondria for further breakdown in order to release energy. Mitochondria have their own DNA which is present in from of loops similar to ­bacterial DNA. It is present in multiple copies in matrix along with ribosomes. However, mitochondrial genome encodes only a few proteins, most of them are encoded in the

13

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Flowering Plants: Structure and Industrial Products

nucleus. Mitochondrial genome of plants is larger in plants as compared with humans, and its size varies among different plants as in Arabidopsis it is 20 times larger, whereas in melon it is 140 times higher than in humans. Mitochondria synthesize energy in the form of ATP (adenosine triphosphate), there­ fore, protein channels in membranes allow for transfer of ADP (adenosine diphosphate), Pi and ATP (also known as ATP and ADP translocators). ATP formation is immediately followed by its export through translocators to other organelles or cytosol of cell ­wherever energy is required within cell. ATP and ADP transport is important for cell as many processes, such as DNA replication, transcription, formation of larger molecules, translation, secondary metabolite formation and cell division are all dependent upon the availability of ATP. Therefore, mitochondria also accumulate near the site where energy demand is high in germinating pollen grain. Mitochondria also play role in cell adaptation to abiotic stress and regulate metabo­ lism of proteins which regulate homeostasis and are involved in programmed cell death. They are also source of providing energy to rapidly growing pollen tube cells. 1.2.4  Plant Vacuoles Store Water, Pigments and Compounds of Defensive Nature

Vacuole of plant cells serve as lytic and storage compartment, which maintains turgor and homeostasis under stress conditions. Storage vacuoles store water, pigments, ­nutrients, crystals, starch, protein bodies for the plant cell and also involved in growth of cell and also help in signaling. Molecules like calcium, sodium, potassium, magne­ sium, chloride, nitrate and water are stored in vacuoles and help increase in height and surface area. Calcium and potassium are required for many processes within plant cells, therefore, vacuoles serve to store them and facilitate their transport within the cell. Vacuoles have many enzymes which convert toxic products into non‐toxic forms. Therefore, they also detoxify harmful products like xenobiotics, as revealed by experi­ mental techniques involving isolation of vacuoles and through replacement of vacuolar content and mutants of vacuoles. Just like membranes of many other organelles, vacuolar membrane or tonoplast is also a lipid bilayer with protein transporters. Vacuoles of floral cells occupy more parts of cell as they store pigments for pollination. They also modulate turgor during growth. Vacuoles also digest old organelles due to hydrolytic enzymes which are no longer required by cells and are therefore known as lytic vacuoles. Mitochondria are transferred to vacuoles by endocytosis. Aquaporins were first discovered in the vacuolar membrane of seeds so named r‐TIP (tonoplast intrinsic proteins). Vacuoles of many pollens are elongated and tubular in shape. In the petals of many flowers, sometimes vacuoles of neighbouring cells store different shades of pigments within the same petal, which differentiates it from the rest of petal, thus making contrasting patterns known as a nectar guide which serve as a guide for pollinators. Vacuolar pH is important factor in determining the color of flowers as an increase in pH may give the blue shade in morning glory (Yagamuchi et al., 2001). This increase in pH is due to an active transport of Na+/K+ from cytosol into the vacuole with the help of Na+/K+ pump. Vacuoles of epidermal cells store pigments like anthocyanin which pro­ tect them against UV radiations. Tonoplast of vacuoles storing anthocyanins pigments require transporters like ATP binding cassettes (ABC). Vacuoles, like protein‐storing

An Introduction to Flowering Plants: Monocots and Eudicots

vacuoles, transfer nutrients to germinating seeds and main source of storing nutrients like Ca, Fe, Mg, P and Zn, thereby serving important role in nutrition. Vacuoles of all plants are composed of H + ‐ATPase, V‐PPase and TIP, such as aquaporins which may differ in their role depending upon their location. Plants vacuoles are also the site for storage of industrially important products like alkaloids and anthocyanins which are widely used in textile and food industries and are reported to have anti‐cancerous properties. Anthocyanins are known to accumulate in pigmented structures within vacuoles known as anthocyanoplasts in plants like red cabbage, which may also contain enzymes for anthocyanins biosynthesis. Channels like H+‐antiports, electrogenic uniport ion and ABC transporters facilitate transfer and accumulation of secondary metabolites in vacuoles. Two proton pumps on vacuolar membrane, that is, V‐ATPases and V‐PPases develop gradient across tono­ plast membrane. Vacuoles are crucial for storage of plants’ defensive compounds in order to prevent toxicity to the rest of the cell. They are also important for synthesis of saponarin which is inhibited without vacuoles (Marinova et al., 2007). New technolo­ gists have developed to express economically important proteins in plants which ­accumulate in vacuoles and can further be used for cultivation of plants so large num­ ber of proteins can be produced at low costs. 1.2.5  Golgi Apparatus

It is involved in the modification of carbohydrates and proteins, and also transports them within the cell wherever they are needed in the form of vesicles. Golgi apparatus also modifies many proteins which are involved in pollination and fertilization pro­ cesses within different floral cells. Within a plant cell, it constitutes a system of stacks of thin vesicles that are held together either in a flat or in a curved array. Individual stacks of cisternae that are filled with fluid with modification are present almost all over the cytosol within plant cell. Golgi complex coordinates with endoplasmic reticulum, and form vesicles, that fuse and form a wider thin vesicle cisternae. Vesicles formed by smooth ER form cisterna on cis face of Golgi apparatus, however, at the trans face, vesicles are released or carried to their destination. These vesicles may move to plasma membrane and discharge their contents. Golgi bodies are also involved in forming cell wall machinery through the same process. 1.2.6  Nucleus Encodes Genes Required for Enzymes Forming Products of Commercial Applications

Nucleus is an important organelle due to the presence of nucleic acids DNA (deoxyribo­ nucleic acid) and RNA (ribonucleic acid). DNA is main heredity material which is ­present on genes present on chromosomes which are thread‐like structures. RNA ­synthesizes proteins for plants growth and metabolism through a process which we call gene expression. All cells of plants possess their own nuclei. However, sieve cells of phloem loss their nuclei upon maturity and they are assisted by companion cells. Nucleus communicates with other organelles and cytosol by means of pores within nuclear membrane. Nuclear envelope is similar to plasma membrane and comprise of phospholipids as dominating lipids. Proteins which are part of nuclear membrane, facilitate transport of molecules and allow mRNA to leave the nucleus through nuclear pore. They also provide passage

15

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Flowering Plants: Structure and Industrial Products

for transport of molecules like ATP from mitochondria within the nucleus to energize energy‐dependent reactions like DNA and RNA synthesis. Nucleotides which are build­ ing blocks of DNA and made up of repeating units of sugar, phosphoric acid and nitrog­ enous bases that are synthesized within the cytosol of the cell. Four nitrogenous bases, adenine (A), guanine (G), cytosine (C) and thymine (T) exist in a pair attached by means of hydrogen bonds. Adenine and guanine form double hydrogen bonds within the cen­ tre of double helical structure. However, guanine and thymine are attached by means of three hydrogen bonds. In RNA, instead of thymine, uracil is present. Nucleus encodes genes for formation of enzymes which are involved in pathways which leads to the for­ mation of products of industrial importance. 1.2.7  Plastids are Sites of Sugar and Fragrance Formation

Plastids are double membrane organelles derived from proplastids, which are undif­ ferentiated plastids in meristematic cells of root and stem. Detailed sequence analysis of genes have revealed that all plastids are evolved from a single ancestral source and thought to be originated by the engulfing of a photosynthetic organism by a non‐­ photosynthetic organism. Like mitochondria, they multiply by division and have mater­ nal inheritance. Plastids possess their own circular genome known as ctDNA (circular DNA) or ptDNA (plastid DNA) which is 120‐160kbp in size and makes up to 0.1% of the size of a nuclear genome. Many enzymes like DNA polymerase, helicase and primase have been purified from them. Angiosperms plastids possess both plastid‐encoded and nuclear‐encoded RNA polymerases (Sato et al., 2003). During cell differentiation, they either differentiate into chloroplasts, chromoplasts or leucoplasts. Leucoplasts are colorless organelles which synthesize lipids and store starch in roots, tubers or seeds. Chloroplasts arise from differentiation of proplastids. They possess their own circu­ lar chromosome and enzymes for gene duplication, gene expression and protein syn­ thesis, however, majority of proteins are encoded in nucleus and later transported to chloroplasts. Chloroplasts are known to be evolved from cyanobacteria because their genome is similar to prokaryotic genome. Chloroplasts are one of the most abundant plastids which are present in leaves of green plants. Their presence in any organ of plant is indicative of their role in formation of sugar through photosynthesis. They contain a lipid bilayer similar to other mem­ branes, however, glycolipids are more common in a chloroplast membrane. Chloroplast lipids like monogalactosyl diacylgylcerols (MGDG) are in fact one of the most abundant lipids on our planet. The membrane of chloroplast is composed of pores which facilitate exchange of molecules and allow them to communicate with the cytosol of cell. Porins in outer membrane of chloroplasts are non‐specific and allow transfer of molecule upto 3 nm in size. However, the inner membrane is composed of specific protein transloca­ tors which allow transfer of molecules between the cytosol and stroma. Pigments which are involved in photosynthesis, that is, antenna pigments which are embedded in the lipid membranes of thylakoids which are disc shaped structures. A  pile of thylakoids make grana which are interconnected through lamellae within chloroplasts. All angiosperms possess chlorophyll a as necessary pigments which are  crucial for light reactions, however, other pigments, that is, chlorophyll ‘b’, ­carotenes and luteins, are also present on thylakoid membranes and transfer energy of

An Introduction to Flowering Plants: Monocots and Eudicots

sunlight to chlorophyll a. Fluid of chloroplast is known as stroma which contains starch grains, free ribosomes and enzymes for formation of carbohydrates during the Calvin cycle. Energy molecules like ATP and NADPH are synthesized through a series of p ­ hotochemical reactions on thylakoids which diffuse in the stroma to provide energy for sugar synthesis. ATP and ADP translocators are present in the inner membrane of  the chloroplast envelope. Plastoglobuli are oil containing bodies which are found within plastids of senescing leaves. Chromoplasts are usually present in the petals of flowers giving red, organ and ­yellow shades. They have an undulated system of membranes without grana. They contain pigments either on the membrane or in the form of plastoglobuli as droplets. During fruit ripening, many chloroplasts are converted into chromoplasts due to the formation of lipid pigments which is evident through a change of color in many fruits like tomato, organ, mango, and so on. They are green when unripened, and turn into chromoplasts when mature. Plastids without pigments and lipids are leucoplasts, they are colorless plastids like amyloplasts. The white color of petals of many flowers is due to leucoplasts. Carotenoids are lipid‐soluble pigments having 40 carbon atoms which accumulate in chromoplasts and give them that orange, yellow and red color to attract pollinators. However, the presence of carotenes in the chloroplast protects antenna pigments against high intensities of light and helps in the absorption of energy for photosynthesis. 1.2.8  Tannosomes are Chloroplast‐Derived Organelles Which Contain Polymers of Tannins

Plants synthesize many molecules in response to the defense against pathogens and  ­herbivores. Proanthocyanidins are type of flavonoids which are also known as ­condensed tannins. They play a defensive role against pathogens and UV radiation. Although tannins inclusions are previously reported to be synthesized by endoplasmic reticulum, recent ultrastructure studies revealed that they are derived from chloroplasts (Brillouet et al., 2013). Figure 1.9 shows developmental stages in the differentiation of chloroplast into tannosomes (tannin‐containing organelles) which involves unstacking and inflation of thylakoids grana forming tannosomes, which are later encapsulated and transferred as shuttle from cytosol to vacuoles where they are stored in order to protect the rest of the cell from toxic effects of tannins. 1.2.9 Ribosomes

are the site for protein synthesis. They are membrane‐bounded structures and consist of one large and one smaller subunit. However, the number of ribosomes depends upon the function of cell where they are present. Plant cells contain fewer ribosomes than animal cells. However, the cells of seeds in legumes contain large numbers of ribosomes. 1.2.10  Endoplasmic Reticulum

(ER) forms part of the endomembrane system and communicates with the nuclear envelope. It is a system of flattened membrane, sacks and tubules. ER without ribo­ somes is smooth endoplasmic reticulum (SER), whereas ER with ribosomes is rough

17

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Flowering Plants: Structure and Industrial Products

Grana

Intrathylakoidal Stromal lumen lamella

Inflating thylakoids Pearling thylakoid

Stroma

Outer Inner membrane membrane Tannosome

Tannins

Shuttle

Stroma Shuttle membrane

CYTOSOL

Tonoplast Tonoplast Stroma Cytosol

Vacuole

Figure 1.9  Stages in formation of tannosomes from chloroplast. During formation of tannosomes, chloroplasts membranes are unstacked and inflated forming tannosomes which are encapsulated and transferred as a shuttle through cytosol to vacuoles where they are stored (Brillouet et al., 2013). Not to scale; (used with permission from Oxford University press).

endoplasmic reticulum (RER) which is involved in protein formation with the help of ribosomes; all the while, SER synthesizes lipids for cells. SER in plant cells also forms a system of transport of molecules in the form of plasmodesmata. It forms phospholipids and proteins for the plasma membrane. RER forms vesicles which transport large ­molecules in coordination with Golgi bodies. 1.2.11 Peroxisomes

are single membrane bounded organelles responsible for oxidative reactions due to catalases and for oxidation of fatty acids. They are involved in detoxification of many waste products. Glyoxysomes convert stored fats into sugars and important in germina­ tion of fat rich oily seeds. They contain enzymes for breakdown of fatty acids through beta‐oxidation. Peroxisomes are thought to be originated either through de novo ­synthesis from invagination of endoplasmic reticulum membrane or through division of preexisting peroxisomes.

An Introduction to Flowering Plants: Monocots and Eudicots

1.2.12 Oleosomes

or oil bodies are spherical organelles which contain triacylgylcerols surrounded by ­protein oleosins in their monolayer phospholipid membrane. They are found in seeds and pollens of many angiosperms. They act as storage sites of many triacylgylcerols. They are detected in tapetum of developing anthers of olive and Arabidopsis. Oleosins are low molecular weight proteins (40

Carotenoids

Cytokinins

Saponin

Carotene Xanthophylls (β-Carotene) (Lutein)

Pinene Farnesene

Tetraterpenoids

Longifolene

Figure 11.2  Terpenoid role within plants depends upon their number of carbon and hydrogen atoms in their isoprene units.

266

Flowering Plants: Structure and Industrial Products

Osmophores may be present in any part of flowers including sepals, petals, carpels or anthers. In epidermal cells they are located on the inner side of perianth with conical, papillate, bullate, rugose, or pileate shapes. Essential oils are also released through glandular epidermal cells or trichomes through rupturing of cuticular vesicle (Figure 11.3). There is no evidence which supports their release through stomatal cells, lenticels or through hydrathodes. A plant may have essential oil ducts or oil glands for storage and secretion of aromatic essential oils in their vegetative parts, or lysigenic oil glands or sometimes intercellular spaces (schizogenic glands) which are filled with aromatic oils. Glandular cells contain a large number of mitochondria and oil bodies which contain essential oils as revealed through transmission electron microscopy. Essential oils may also form a bond with carbohydrates in the form of glycosides which released through the breakdown of glycosidic bonds. Heat also promotes their evapo­ ration in atmosphere. In many member of Lamiaceae, formation of monoterpenoids take place within special­ ized secretory cells, however, their accumulation takes place in epicuticular cavities of glandular trichomes. In woody plants, they are secreted in resin ducts. In Arabidopsis, emission of volatile compounds is reported through flowers. Plants have two types of glandular trichomes depending upon their role in protection against pathogens. Short‐ term glandular trichomes which are present in young tissues and end secretion rapidly. In long‐term trichomes like in mature orange, secretory molecules are accumulated below the cuticle layer. However, the emission of floral volatiles change rhythmically within a day. There are many mechanisms which are proposed regarding the release of volatile molecules from epidermal cells but no exact mechanism was known about how they are actually emitted until now. Some studies reported that after their biosynthesis in plas­ tids, they are transported to cytosol. They are further modified in ER and exported from plasma membrane into the apoplast of epidermal cells making cuticle permeable and are released at the cuticular surface. Protein‐mediated transport or direct vesicular transport is also suggested to occur. They may also develop direct contact in mem­ branes of ER and cell membranes which create a lipophilic pathway for their intracel­ lular trafficking. The role of ABC proteins and lipid transfer proteins is also reported. A gradient developed between the cuticle and the cell wall of flower cells may also act as a driving force for the release of volatile oils. 11.2.3  Formation of Monoterpenoids Like Menthol is a Part of Chemical Defense of Mint and Other Plants

Monoterpenoids synthesis and the site of storage within a tissue depends upon its role. As menthol repels insects, the synthesis of menthol takes place in glandular hair of leaves of M. piperita. (Figure  11.4). Due to the sensitivity of mint plant to insects, menthol translocation in the form of neo‐menthol glucoside takes place from phloem to the root where menthol is stored and protects the roots from insects in soil. Neo‐menthol is syn­ thesized from limonene and geranyl‐pyrophosphate in the mesophyll cells of mint leaves. 11.2.4  Linalool is a Defensive Terpenoid and a Volatile Attractant

Linaool also known as linalyl alcohol or linalyl oxide is a common aromatic a­cyclic monoterpenoids from the flowers of many plants belonging to families Lami­ aceae, Lauraceae, and Rutaceae. More than 200 plants are known to synthesize linalool.

(c)

DOXP

(b) G-3-P

Trichome

Pyruvate

DOXP 2 (Isopentenyl pyrophosphate) Geraniol (a) Epidermal cells

Petal cell

DOXP pathway synthesizes geraniol in rose plastids

Plastid

Geraniol biosynthesis in petal & release through trichome

Figure 11.3  (a‐c) (a) Synthesis and release of volatile terpenoids, (b) DOXP (1‐deoxy‐D‐xylulose 5‐phosphate pathway) synthesizes volatile terpenoids in plastids, (c) which are either stored or immediately released through modified structures located on epidermal cells.

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Flowering Plants: Structure and Industrial Products

Geranyl pyrophosphate (b)

Limonene Isopiperitenol Isopulegene

Isopiperiterone

Pulegone

Piperitenone

Menthenone

Piperitone

Neomenthol

Menthol

Neomenthyl Glucose (45%)

Menthol Acetate

Menthol biosynthesis

Phloem

Menthol carried to root cells (a) Mentha piperita (Menthol acts a repellent. It is biosynthesized in leaves & transported through phloem to root where it protect root from insects.)

Insect & bacterial repellent

(c) Menthol transportation

Figure 11.4  (a‐c) Formation of menthol is a defensive mechanism of mint (Mentha piperita). (a) Mint plant, (b) Menthol synthesis takes place in leaves of mint plant from GPP which forms limonene and then isopiperitenol. Formation of isopiperitenol acts as a branching point during menthol biosynthesis, forming isopulegene and isopiperiterone. Isopulegene synthesizes pulegone which forms menthenone. Menthenone is further converted in neomenthol which forms neomenthyl glucoside. However, isopiperiterone forms piperitenone which is further converted in piperitone. Piperitone formation is followed by menthol formation, (c) Menthol is translocated through phloem from leaves to the root of mint plant where it acts as a repellent.

It acts both as a defensive compound as well as a volatile attractant mostly for moths. Some important plants include Aniba rosaeodora (rosewood tree), Cinnamomum verum, Citrus, and Mentha spp. Linalool is also known to be toxic to young tissues, therefore, many organs tend to produce it only when they are mature. It is also used in many insecticidal products due to its insecticidal properties. Linalool synthase catalyzes the conversion of geranyl pyrophosphate to linalool in the petals of leaves where it is bound to plasma membrane. Linalool is predominantly pro­ duced by epidermal cells of petals so it can easily diffuse from petals in plants like Clarkia breweri. Essential oils of Coriandrum sativum L. are composed of 65–78% of linalool while A. rosaeodora upto 86%. However, amount and composition of essential oil of same spe­ cies may also differ due to different geographical environments as C. sativum which is indigenous to Asia comprises linalool less than 55%. In addition to linalool, coriander vola­ tile oil also is composed of cymene, nerol, carvacrol and geranyl acetate (Figure 11.5).

Floral Essential Oils: Biosynthesis, Classification and Commercial Applications Volatile signals for pollination & defense

Attracts insect or a fly for pollination

Fruit essential oils Linanool, α-Pinene, α-Terpentine, Geranyl acetate, Camphor, Geraniol, β-Pinene, Myrcene, Limonene, P-cymol, Dipentene

CH

2O

CH2OH OH

Repels bacteria

H

OH

α-Terpentine, α-Decylaldehyde, Borneol, Acetic acid ester

Cuticle

DMAPP+IPP

Volatiles released in cytosol

Geranyl pyrophosphate Geraniol Linalool synthase synthase Geraniol

Mature leaves

Linalool

Plastid

Trichomes

(b) Leaf showing glandular trichomes

(a) Coriandrum sativum

(c) Trichome showing monoterpene formation in plastid

Cold water

Still

Hot water

H

O

2

CH2OH

CH

Steam

OH

Cooling coil

CH2OH CH Linalool

Nerol

Geraniol

Sieve

H

O

2

Essential Volatiles

CH2OH

Essential oils Condenser Water

OH CH

CH2OHO

H

2O H OH

Water & essential oil Fire Floral water

Figure 11.5  (a‐d) Linalool, a monoterpenoid, acts as a defensive compound and a volatile attractant. It is known to be synthesized by over 200 plants. Many members of family Apiaceae synthesize linalool as a part of their defense to keep their predators away. (a) Coriandrum sativum plant, (b) In C. sativum, linalool synthesis takes place within plastids of glandular trichomes located on epidermal cell from where it diffuses in air, (c) DMAPP and IPP serve as precursors for synthesis of essential oil of C. sativum which is a mixture of many volatile monoterpenoids, including linalool, geraniol, and many other volatile molecules (shown in (a)), (d) Extraction of essential oils like linalool from linalool‐synthesizing plants like C. sativum is done through steam distillation method which is a temperature sensitive method used commonly for extraction of essential oils and results in the separation of volatile molecule from plant tissues. Volatile molecules are passed through condenser in which vapors are condensed and essential oils are then collected in another vessel along with floral water, (c) Linalool is commonly used essential oil in many cosmetic and pharmaceutical products. (See insert for color representation of the figure.)

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Flowering Plants: Structure and Industrial Products

Linalool containing cosmetic products

Face cream

Figure 11.5 (Cont’d)

Transcripts of linalool oxides are expressed during pollen growth of Clarkia breweri in the transmitting tissue of stigma and style as well as in petals where they are known to guide insects to stigma and also inhibit pollen growth of other species (Dudareva et al., 1996). However in snapdragon flowers, genes for terpene synthase forming lin­ alool, myrcene, ocimene and nerolidol are expressed in upper and lower petal lobes which are main sites involved in synthesis and release of these volatile terpenoids (Nagegowda et al., 2008). In Arabidopsis, monoterpenes and sesquiterpene synthases are expressed in stigma, anthers, sepals and nectaries which indicate their defensive role in herbivore and pro­ tection against microbial pathogens (Tholl et al., 2005). However, plants minimize their energy requirements by secreting linalool only when flower is ready for pollination and its emission stops soon after pollination is completed. In plants of family compositae, linalool synthesis in petals starts at the same time, whereas floral initiation starts later. Linalool is widely used in many food products and for making perfumes. Linalool‐ based cosmetic and food products are available in markets. They include many skin care products, hair shampoos, soap bars and perfumes. Linalool content is also being increased in some plants to increase the crop yield of plants which grow outside the range of their pollinators in order to make pollination more efficient. Limonene is another important aromatic compound of lemon that is found in leaves and peel of lemon fruit. Limonene synthase uses geranyl pyrophosphate as a substrate to synthesize limonene, myrcene, and pinene, and this may be one of the reason for the abundance and diversity of plant terpenoids. 11.2.5  Geraniol: A Volatile Attractant and Defensive Essential Oil in Cosmetic and Medicinal Products

Geraniol is an important monoterpenoids which is produced by wide variety of plants and it is one of the commonly used ingredients in many cosmetic, food and pharmaceu­ tical products. It forms an important part of the essential oil of geranium and rose spp. Cymbopogan martinii and C. winterianus are also important commercial sources of geraniol. Difference in geraniol content is reported in different species of Cymbopogan.

Floral Essential Oils: Biosynthesis, Classification and Commercial Applications

Essential oil of C. martinii is composed of upto 95% of geraniol, whereas C. flexuosus has 35–47% and Litsea cubeba has 38–45% of geraniol. Essential oil of C. martinii is low in geraniol content and referred as gingergrass oil or Indian geranium oil. Essential oil from Cymbopogan species are used to treat cough, fever, leprosy, gout and stomach disorders. Many aroma chemicals distilled from Cymbopogan species are used in per­ fume blending. Oil of Cymbopogan wnterianus and C. nardus is commercially sold with the international trade name of Oil of Citronella which is produced worldwide at 2000 tonnes. They are aromatic grasses grown in many Southeast Asian countries. Oil of lemongrass is extracted from C. flexuosus and C. citratus. Palmarosa oil is extracted from C. martinii var. motia, whereas gingergrass oil is from C. martinii var. sofia. The commercial source of vetiver oil is Vetiveria zizanioides. Geraniol is often found with geranial and neral, which are oxidation products of geraniol. Geraniol is an important essential oil which is used in many pharmaceutical, food cosmetics and perfume products. It is used in many cosmetic products to make them fragrant like soap bars, shampoos, skin care products, and perfumes. It is also used to add flavor to tobacco products. It also as acts as a mosquito repellent. Geraniol‐based perfumed or deo‐perfume edible candies are also available in the market. Geraniol p­ermeates through skin after eating these candies and fragrance is released through skin (Figure 11.6). Different chromatographic techniques are used for the separation and isolation of monoterpenes. However, nature of conjugation can be determined through ultraviolet spectroscopy. Mass spectrometry and x‐ray analysis is used for elucidating the structure of terpenoids.

Figure 11.6  Deo‐perfume is an edible candy made with the fragrance of rose which makes skin permeable and fragrant.

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11.3  Many Terpenoids are Insecticidal and Act as Allelochemicals Volatile chemicals released by clary sage (Salvia sclaria), that is, camphor, 1, 8‐cineole, pinene and diterpenes inhibit DNA synthesis and seed germination of many weeds, acting as allelochemicals. Camphor produced by many plants like Cinnamomum camphora, Rosmarinus officinalis, and Ocimum basilicum through the geranyl pyrophos­ phate are important allelochemicals. Other known allelochemicals are carvone, linalool, methyl chavicol and anethol. Pyrethin from pyrethrum daisies possesses insecticidal properties. Dried flower heads are pyrethrum daisies, whereas extracted active ingredi­ ents are called pyrethin. Pyrethin‐based shampoos are used to kill lice on pets. Plants from families Fabaceae, Lamiaceae and Verbenaceae, possess strong insecticidal activi­ ties against a lot of insect pests and can serve better substitute for synthetic compounds like methyl bromide and phosphine due to their availability and degradability; they also are less toxic to the environment (Figure 11.7).

11.4  Sesquiterpenes are Defensive Terpenoids of Many Plants Many sesquiterpenes are composed of three isoprene units (C15H24) which are involved in defensive mechanisms and act as pheromones. Almost 5000 sesquiterpenes lactones are known to be synthesized by wide range of plants, however they are commonly found in families like Cactaceae, Solanaceae, Araceae and Euphorbiaceae. They are present in many members of sunflower family in specialized secretory cells, that is, laticifers. However, sesquiterpenes which are involved in the defense against pathogens are found in vacuoles. Sesquiterpenes exist in the latex of many plants as one of the dominant metabolite in order to protect them from herbivores. They also act as allelochemicals signals. In plants like Aquilaria sinensis they are produced only in response to herbivory. Sesquiterpenes are formed by combining ISPP with geranylgeranyl pyrophosphate with the help of enzyme farnesyl pyrophosphate (FPP) in endoplasmic reticulum. Important sesquiterpene include farnesene, nerolidol, zingiberene, caryophyllene, patchoulol and longifolene. Capsidiol is phytoalexin formed in pepper and tobacco. They make up an important part of our diet as lettuce and chicory and star anise are important sources of sesquiterpene lactones. Farnesol exists in green apple coating, flowers, leaves and roots of Martricaria spp., and are responsible for their aroma. It serves as a precursor for the formation of sesquit­ erpenes in plants and acts as potent agent against storage pest and fungal pathogens. Many sterols like brassinosteroids in plants, saponins, yamonin from yam plant (Dioscorea), cardenolides like digitoxigenin and defensive substances like phty­ oecdysones are synthesized from farnesyl phosphates. Konrad Bloch received the Nobel Prize in 1964 for elucidating that acetly‐CoA serves as a precursor for biosynthesis of steroids. Essential oils with blue‐green color are composed of chamazulene in chamomiles. Cayophyllene is secreted by stems and flowers of Cannabis sativa, Ocimum basilicum,

Floral Essential Oils: Biosynthesis, Classification and Commercial Applications

(a)

(b)

(c) (f)

(d)

(e)

Figure 11.7  (a‐f) Essential oil of Lantana spp. possesses strong insecticidal and repellents effects against the maize grain weevil, (b) Aromatic oil of M. piperita is composed of linalool and menthol pulegone, menthone, and carvone. However, the proportion of limonene decreases with the age of plant but menthone increases and converts into menthol (Gershenzon et al., 2000), (c) Essential oils of Ocimum spp. O. suave, O. basilicum, O. kilimandscharicum are used in making biopesticides against mosquitoes (when used in mosquito coil, 93–95% activities against killing of mosquitoes). O. basilicum (sweet basil) synthesizes nerol and geraniol which are stored in peltate glands of leaf epidermis. Geraniol synthase (GES) synthesizing geraniol is localized in glands, (d) Azadirachitin is the most important limnoid of Melia azedarach. Nimbin and nimbidin have anti‐viral and anti‐fungal properties useful to humans and animals. Gedunin, a minor limonoid, is effective in treating malaria through leaves infusion

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Flowering Plants: Structure and Industrial Products

(g) “I have genes from lemon, I am more stronger than you!”

Hey! “let’s run, he is going to kill us.” L

Figure 11.7 (Cont’d)  (e) Leaves of Ricinus communis possess insecticidal, anti‐larval and ovicidal activity against mosquito larvae and contain isoquercetin, 2,5‐dihydroxybenzoic, and epicatechin, (f ) St. John’s wart essential oil is commonly used in perfumery and blends well with clary sage, lavender, cedar, vetiver, rosemary and chamomile, (g) Cartoon illustration of transgenic bacteria with limonene which acts as anti‐bacterial volatile oil.

Origanum vulgare, Rosmarinus officinalis, and Syzygium aromaticum. It gives spiciness to fruit of Piper nigrum. Nerolidol makes essential oil of Citrus aurantium, Cymbopogan citratus, Jasminum sambac, Lavendula angustifolia, Melaleuca alternifolia and Z.  officinale and is used as a flavoring agent in perfumery due to its woody aroma. Zingiberene synthesized by cells of rhizome gives flavour to ginger.

11.5  Diterpenoids are Important Phytohormones Which Comprise of Four Isoprenoid Inits Diterpenoids are composed of four isoprenoid units with 20 carbon atoms which are derivative of geranylgeranyl pyrophosphate. They include compounds like abietol, pimarinol, sciarcol and manool. Retinol and retinal phytol are diterpenoid derivatives. Many genera of family Euphorbiaceae produce economically important diterpenoids in their parenchmya cells (Figure 11.8). One of the diterpenoid ingenol mebutate is used for  the precancerous skin disease. Resiniferatoxins and prostratin are used for the t­reatments of severe pain and HIV (King et al., 2014).

Floral Essential Oils: Biosynthesis, Classification and Commercial Applications

(a)

(b)

(c)

(d)

(e)

Figure 11.8  (a‐e) Many Euphorbia spp. and plants from family Euphorbiaceae synthesize many terpenoids within their latex along with other phytochemicals, (a & b) E. rolyeana is composed of ingol and ingenol diterpenes which are synthesized in stem and leaves, (c) Role of E. helioscopia is being investigated for its possible anti‐HIV activity, (d) E. cotinifolia contain many terpenoids and flavonoids which have activities against phytopathogens bacteria, (e) Milky latex produced by E. splendens is a complex mixture of alkaloids, terpenoids, tannins, oils and resins and is toxic for herbivores.

Gibberellic acid is an important phytohormone, a diterpenoid, crucial for growth and development of plants. Many conifer resins are complex mixture of monoterpenes and sesquiterpenes. They form turpentine fraction which is composed of limonene and toxic for many insects and fungi. However, diterpenes form rosin fractions of conifer resins constitute resin acids containing abietic acids. They are stored as oleoresins in resin channels and secreted upon wound or injury to protect the infected sites. Enzymes for diterpenoid resin synthesis are isolated and assayed through liquid scintillation spectrometry using acetic acid as substrate.

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Plants like Hypericum perforatum commonly known as St. John’s wort, synthesize medicinal phytochemicals like hypericin, pseudohypericin and hyperforin. Hypericins accumulate in dark red color oil glands within in the leaves and flowers, whereas h­yperforins accumulate in flowers of plants. Many of these compounds are known to be anti‐carcinogenic, antidepressant, anti‐viral and antibiotic activities.

11.6  Terpenoid Biosynthesis in Plants Proceeds in Two Different Cellular Compartments Terpenoid biosynthesis in plants takes place within cytosol as well as within their plas­ tids through different pathways. However, their end products, that is, five‐carbon con­ taining compounds isopentenyl pyrophosphate (ISPP) and many enzymes which are involved in their biosynthesis are the same within cytosol and plastids. Terpenoid syn­ thesis occurs in cytosol through mevalonic acid pathway (MVA) and in plastids through methyl erythritol 4‐phosphate pathway (MEP). During terpenoid biosynthesis in cytosol through MVA pathway, acetyl‐CoA serves as a precursor for synthesis of terpenoids. Enzyme AcAc‐CoA thiolase (AACT) cata­ lyzes the condensation of two molecules of acetyl‐CoA which results in the formation of acetoacetyl‐CoA (AcAc) (Figure 11.9). In the next step, AcAc is converted into HMG‐ CoA in another condensation reaction with another molecule of acetyl‐CoA. This step is catalyzed by enzyme HMG‐CoA synthase. HMG‐CoA is further acted on by an enzyme HMG‐CoA reductase which leads to the formation of mevalonate. Phosphorylation of mevalonate by phosphomevalonate kinase (PMK) forms meva­ lonate‐5‐phosphate in downstream steps. Another phosphate group is added to meva­ lonate‐5‐phosphate by enzyme mevalonate diphosphate which results in formation of mevalonate‐5‐diphosphate which further forms IPP by enzyme mevalonate diphos­ phate decarboxylase (MVD) in a decarboxylation reaction. In an isomerization reac­ tion, an isomer of IPP, that is, dimethylallyl diphosphate (DMAPP), is formed by enzyme isopentenyl diphosphate isomerase (IDI). In tobacco BY‐2 (TBY‐2) and in C. aureus using [2‐13C,4‐2H]deoxyxylulose double‐labeling studies, it is revealed that regulation of DMAPP and IPP balance is different among plant species (Tritsch et al., 2010). Pyruvate and glyceraldehye‐3‐phosphate (GA‐3P) act as precursor for formation of IPP and DMAPP in MEP pathway in plastids. Initially, 1‐deoxy‐D‐ xylulose‐5‐phosphate (DOXP) is formed in a condensation reaction catalyzed by enzyme DOXP synthase (DXS). DOXP is converted into MEP by DOXP reductoisomerae (DXR). MEP is further acted upon by enzyme 2‐C‐methyl‐D‐erythritol 4‐phosphate cytidylyltransferase (MCT) to form 4‐(cytidine 50‐diphospho)‐2‐C‐methyl‐D‐erythritol (CDP‐ME). Next 4‐(cytidine 50‐diphospho)‐2‐C‐methyl‐D‐erythritol phosphate (CDP‐ME2P) is formed by enzyme CMK. In the next step, enzyme 2‐C‐methyl‐D‐erythritol 2,4‐ cyclodiphosphate synthase (MDS) converts CDP‐ME2P in another intermediate, that is, 2‐C‐methyl‐D‐erythritol 2,4‐cyclodiphosphate (ME‐2,4cPP) which is further acted upon by enzyme (E)‐4‐ hydroxy‐3‐methylbut‐2‐enyl diphosphate synthase (HDS) to form (E)‐4‐hydroxy‐3‐ methylbut‐2‐enyl diphosphate (HMBPP). Branching of HMBPP to IPP and DMAPP is  catalyzed by simultaneous action of enzyme (E)‐4‐hydroxy‐3‐methylbut‐2‐enyl d­iphosphate reductase (HDR). Interconversion of IPP into DMAPP takes place through isopentenyl diphosphate isomerase (IDI).

Floral Essential Oils: Biosynthesis, Classification and Commercial Applications

Figure 11.9  Biosynthesis of volatile terpenoids in plants takes place either through mevalonate pathway (MVA) which takes place in cytosol or in plastids through methylerythritol pathways (MEP). Mitochondria also synthesize sesqueterpenoids from IPP (isopentenyl pyrophosphate). Boxes represent enzyme and volatile terpenoids are underlined. Abbreviations: AACT, acetoacetyl‐CoA thiolase; AcAc‐CoA, acetoacetyl‐CoA; CDP‐ME, 4‐(cytidine 5′‐diphospho)‐2‐C‐methyl‐d‐erythritol; CDP‐ME2P, 4‐(cytidine 5′‐diphospho)‐2‐C‐methyl‐d‐erythritol phosphate; CMK, CDP‐ME kinase; DMAPP, dimethylallyl diphosphate; DOXP, 1‐deoxy‐d‐xylulose 5‐phosphate; DXR, DOXP reductoisomerase; DXS, DOXP synthase; FDS, farnesyl diphosphate synthase; FPP, farnesyl diphosphate; GA‐3P, glyceraldehyde‐3‐phosphate; GDS, geranyl diphosphate synthase; GGDS, geranyl geranyl diphosphate synthase; GGPP, geranyl geranyl diphosphate; GPP geranyl diphosphate; HDR, (E)‐4‐hydroxy‐3‐methylbut‐2‐enyl diphosphate reductase; HDS, (E)‐4‐hydroxy‐3‐methylbut‐2‐enyl diphosphate synthase; HMBPP, (E)‐4‐hydroxy‐3‐methylbut‐2‐enyl diphosphate; HMG‐CoA, 3‐hydroxy‐3‐methylglutaryl‐CoA; HMGR, HMG‐CoA reductase; HMGS, HMG‐CoA synthase; IDI, isopentenyl diphosphate isomerase; IPP, isopentenyl diphosphate; ISPS, isoprene synthase; MCT, 2‐C‐methyl‐d‐erythritol 4‐phosphate cytidylyltransferase; MDS, 2‐C‐methyl‐d‐erythritol 2,4‐cyclodiphosphate synthase; ME‐2,4cPP, 2‐C‐methyl‐d‐erythritol 2,4‐cyclodiphosphate; MEP, 2‐C‐methyl‐d‐erythritol 4‐phosphate; MVD, mevalonate diphosphate decarboxylase; MVK, mevalonate kinase; PMK, phosphomevalonate kinase; TPS, terpene synthase (Nagegowda, 2010). (Used with permission of Elsevier.)

Presence of prenyltransferases in cytosol and plastids form prenyl diphosphates from IPP and DMAPP. Enzyme geranyl diphosphate synthase (GDS) produce 10‐C geranyl diphosphate (GPP) which serves as a universal precursor of monoterpenes. A variety of monoterpenes and sesquiterpenes are formed by action of terpene synthases (TPSs) (Nagegowda, 2010). Sesquiterpenes synthases synthesize 15‐C terpenes which are reported to be localized in cytosol. In strawberries, a bifunctional nerolidol and linalool

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synthase (FaNES1) is detected to be localized in cytosol as revealed through GFP l­ocalization study and chloroplasts assays. Further, 15‐C farnesyl pyrophosphate (FPP) can be formed in a condensation reaction of DMAPP and two molecules of IPP by enzyme farnesyl diphosphate synthase (FDS). However, spatial and temporal expression of terpene synthases in plants suggest that terpenoids synthesis is regulated by transcriptional control. Environmental factors like heat, temperature, and sunlight also control terpene synthase expressions. However, formation and release of volatile compounds in flowers like snapdragon is regulated at transcriptional level (Muhlemann et al., 2012). Modern methods for extraction and identification of commercially important e­ssential oils include thin layer chromatography and gas chromatography, identification by retention time, infrared spectroscopy, carbon‐13 nuclear magnetic resonance s­pectroscopy and mass spectroscopy. Isolation is achieved by headspace methods, direct vaporization and liquid CO2 extraction. 11.6.1  Vanillin Biosynthesis

Vanillin is another important fragrant molecule which is synthesized by Vanilla planifolia and V. tahitenses although trace amounts are synthesized by other plants. Aroma of Vanilla is due to 200 molecules however, main constituent is vanillin. Vanilla pods are major source of commercial vanillin. Vanillin also acts as defensive compound and stored in pods as vanillin glucosides which when hydrolyzed releases vanillin. Phenylalanine acts as a precursor of vanillin biosynthesis. During vallinin synthesis, phenylalanine forms cinnamic acid through enzyme phenylalanine ammonia lyase (PAL)  which converts into p‐caumaric acid by cinnamate‐4‐hydroxylase (C4H). Next p‐Coumaroyl‐CoA is formed by 4‐hydroxycinnamoyl‐CoA‐ligase (4CL). In further steps, quinate and shikimate esters are formed leading to the formation of caffeic acid through caffeoyl‐CoA (Figure 11.10). The formation of caffeic acid leads to ferulic acid formation which is converted into vanillin. The conversion of ferulic acid to vanillin is catalysed by enzyme vanillin synthase, that is, VpVAN and proceeds in two partial reactions which involve an initial hydration addition reaction followed by a retro‐aldol elimination r­eaction. (Figure 11.11). VpVAN is localized to inner part of vanilla pod and catalyzes the conversion of ferulic acid in vanillin. Higher transcripts levels of enzyme are found in single cells located a few cell layers away from the inner epidermis (Gallaj et al., 2014). Mayu Yamamoto got the Nobel Prize in 2007 for extracting lignin from cow dung and converting it into vanillin. Vanillin is used to make L‐dopa to treat Parkinson’s disease. Naturally extracted vanillin makes only 0.4% of food industry, whereas the remaining is chemically synthesized. Mostly synthetic vanillin is obtained from petrochemical sources. Artificial vanilla essence is used to add flavours to chocolates and drinks, however, through gas‐liquid chromatography, real and synthetic vanilla flavour can be distinguished.

11.7  Economically Important Terpenoids Many aromatic monoterpenes are well known for their antimicrobial properties and therefore make an important part of human diet in form of many herbs and spices. They also help plants in maintaining homeostasis. Due to their medicinal values they are

(a)

O OH NH2

Phenylalanine Phenylalanine ammonia lyase (PAL) O OH

Cytochrome P450 reductase (POR) 2e–

Cinnamic acid O2 Red Cinnamate 4-hydroxylase (C4H) Ox H2O

O OH

*HO

Hydroxycinnamoyltransferase O (HCT)

ρ–Coumaric acid 4-hydroxycinnamoyl-CoA ligase (4CL) O SCoA

Sh/Q

*HO *HO ρ-Coumaroyl CoA 4-Coumaroyl shikimate/quinate O2 Red Coumaroyl ester 3′-hydroxylase (C3′H) Cytochrome P450 reductase Ox CYP98A3 orthologue (POR) – 2e H2O O Hydroxycinnamoyltransferase O (HCT) HO HO Sh/Q SCoA HO HO Caffeoyl shikimate/quinate Caffeoyl CoA 4-Hydroxycinnamoyl-CoA ligase (4CL) O HO

OH

*HO Caffeic acid Caffeic acid/5-hydroxyferulic acid O-mehyltransferase (COMT) O MeO

MeO

O

MeO

O

*HO

Glucose-O Vanillin glucoside

*HO

Vanillin Vanillin synthase (VAN) hydratase/lyase

(b) COOH

COOH HO

OCH3 OH Ferulic acid

OH Ferulic acid

Q, quinate; Sh, shikimate OH* indicates that glucosylation can occur at this point during the formation of vanillin glucoside

CHO

VPVAN OCH3 OH

VPVAN OCH3 CH3COOH OH Vanillin

Figure 11.10  (a‐b) Vanillin is a defensive compound which is synthesized within pods of Vanilla spp., (a) Enzyme vanillin synthase (VpVAN) catalyzes de novo biosynthesis of vanillin through cleavage of ferulic acid and its glucoside to produce vanillin and vanillin glucoside, (b) The conversion of ferulic acid to vanillin byVpVAN takes place sequentially by two partial reactions which involve an initial hydration addition reaction followed by a retro‐aldol elimination reaction (Gallage et al., 2014). (Used with permission.)

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Flowering Plants: Structure and Industrial Products

(a)

(b)

(c)

Figure 11.11  (a‐c) Enzyme VpVAN synthesizes vallinin from ferulic acid in V. planifolia. It is localized to an inner part of the pod: (a) Detection of VpVAN transcripts through FITC‐conjugated antibodies which recognize digoxigenin (DIG) incorporated in the specific PCR products and represents VpVAN transcript, (b) same image at higher magnification, (c) Fluorescence shows unspecific binding of the FITC‐conjugated antibodies recognizing DIG to cell walls and supporting fiber cells surrounding the vascular systems. Note chloroplasts are visible (as orange dots) due to their auto fluorescence at the used filter settings. Abbreviations: e, epidermis; c, cortex; cl, chloroplast; s, supporting fibre tissue; Scale bar, 100 µm. (Gallage et al., 2014). (Used with permission.)

used in many pharmaceutical products. Many essential oils are part of our daily food due to their aromatic, anti‐microbial, anti‐carcinogenic and anti‐inflammatory proper­ ties. Commonly used aromatic compounds are antheol, cuminyl alcohol, limonene, geraniol, thymol, linalool, eugenol, capsicin, menthol, piperine and zingiberone. Many of them are used in flavouring like ginger, cordamom, cumin, fenugreek, saffron and clove. Vanilla extracts and oleoresins are widely used by food and beverage industries, in frozen dairy, desserts, puddings, custards, ice creams like cream caramel, cream b­rulee, peach melba, and apple. Many terpenoids act as natural blockers by protecting the plants from harmful radiations. Therefore, terpenoids from Melaleuca cajuputi which secrete platyphyllol are being used by many sun‐blocker manufacturing companies. Nelumbo nucifera is

Floral Essential Oils: Biosynthesis, Classification and Commercial Applications

reported to stimulate melanin synthesis and tyrosine activity due to its terpenoids (Jeon et al., 2009). It is also effective in the development of gray hair‐preventing chemicals. Some plant‐derived medicinal products which contain diterpenoids include forskolin and ingenol‐3‐angelate. They are used for cardiovascular and skin cancer treatments. Patchoulol from Pogostemon cablin is source of the chemotherapic drug Taxol. Essential oils of Melaleuca alternifolia has antiviral activity against Herpes simplex virus type 1(HSP‐1 and HSP‐2). The antiviral activity of some essential oils is also demonstrated against poliovirus, adenovirus and influenza virus. Linalool is known to have the strong­ est activity against adenoviruses. Menthol is classified as topical analgesic and can cause a feeling of coolness due to stimulation of ‘cold receptors’ by inhibiting the Ca2+ cur­ rents of neuronal membranes. Abietane diterpenoids from Clerodendrum eripophyllum roots have antimicrobial and antiparasitic properties (Machumi et  al., 2010). Many diterpenoids are being explored for their analgesic, anti‐microbial, anti‐fungal and psy­ choactive properties. Essential oil of Lavendula hybrida has analgesic efficacy when administered through the inhalatory route. Lavender oil with its constituents like linalool, linalyl acetate and 1,8‐cineole, are effective against ulcer and can alleviate pain. Essential oil of Salvia africana‐lutea and Dodonaea angustifolia also exhibit analgesic activities. Perillyl alcohol and limonene have potential against breast cancer and pancreatic tumors. Syzygium aromaticum essential oil has anti‐carcinogenic and anti‐mutagenic activities. Geraniol exhibits anti‐carcinogenic by reducing polyamine metabolism, a process involved in cancer proliferation. Terpenoids of plants like Tanacetum parthenium, Yarrow (Achillia spp.), and quinghaosu (A. annua) are used in the treatment of malarial type ailments both in traditional and medicinal treatments. Many medicinally important plants in sunflower family contain sesqueterpenoids. Sesquiterpene lactones from members of this family are used to impart bitterness of alcoholic drinks. Caryophyllene is widely used in food and beverage products, creams, lotions and detergents and a key component of balm of Gilead. Products like Charlotte. ‘Amouge’, ‘Jicky’, and ‘Habanita’ include vanillin as principal note. The pharmacological value of vanillin is also known due to its role as carminative, aphrodisiac, antimetastatic and antiangiogenic activities. Vanillic acid is also useful in sickle cell. It is also used to add flavour to pharmaceutical products. 11.7.1  Bio‐engineered Terpenoids

Metabolic engineering of volatile terpenoids has provided information about the p­resence of GPP and FPP pools in plastids, mitochondria and in cytosol and about silent metabolism of some enzymes which do not have endogenous substrate. A web‐based database, that is, www.atipd.ethz.ch is constructed known as Arabidopsis thaliana Isoprenoid Pathway Database (AtIPD). This pathways is based on the informa­ tion from isoprenoid pathway models and genes from public metabolic pathways data­ bases like BioPathAt (Lange & Ghassemian, 2005), AraCyc (www.arabidopsis.org/ biocyc) KEGG (www.genome.jp/kegg) and SUBA (suba.plantenergy.uwa.edu.au). They serve as valuable resources for investigation of regulation of carotenoid pathway through quantitative technologies and systems biology. MASCP Gator web portal (gator. mascproteomic.org) also provides resources to Arabidopsis community. AtCHLRO is

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another important database which gives information about biosynthesis of isoprenoids. It makes use of extensive proteomics data about peptide sequencing, molecular weight, chromatography retention times, MS/MS spectra, spectral count, corresponding to  proteins in highly purified leaf chloroplasts and their envelopes, stroma, and thylakoids.

11.8  Future Challenges Although terpenoids‐synthesizing pathways are being genetically engineered in many plants in order to provide defense against pathogens, to extract natural fragrances for their applications in different industries, it has been successful only in limited number of species so far. Use of essential oils with anti‐microbial, and pesticidal properties is increasing in food and agricultural industries and replacing use of synthetic preserva­ tives which are harmful for health. However, introduction of many of these products in market is still a challenge due to poor coordination among researchers and industries, due to tedious process of registration of product in order to be approved by EU which is also expensive and involves toxicity testing. There is a need to development efficient ways of bioactive packing of antimicrobial compounds which maintain their higher encapsulation efficiencies which are a­cceptable by European legislation in order to increase their use in food industries. More research should be conducted to introduce plants based insecticides market and there is a need to develop transgenic bioinsecticidal plants. Agriculture industry is still searching for genes involved in terpenoids‐synthesizing enzymes which can be cloned and overexpressed in edible plants and cereals which are sensitive to pathogen attacks. There is need to conduct sufficient research in making ter­ penoids based pesticides to protect crops from pests. Similarly, characterization of linalool synthase expression can also fill the gaps regarding the evolution of fragrant species into non‐fragrant species about how they lost the tendency to synthesize f­ragrant molecules.

References Abdullaev, J.F., Cabarello‐Ortega, H., Rivero’n‐Negrete, L., Pereda‐Miranda, R., Rivera‐ Luna, R., Manuel Herna’ndez, J., Pe’rez‐Lo’pez, I., & Espinosa‐Aguirre, J.J. (2002). ‘In vitro evaluation of the chemopretentive potential of saffron’, Revista de Investigacion Clinica, 54, pp. 430–436. Christmann, M. & Wallach, O. (2010). Angewandte Chemie International Edition, 49, p. 9580. Dudareva, N., Cseke, L., Blanc, V.M., & Pichersky, E. (1996). ‘Evolution of floral scent in Clarkia: novel patterns of S‐linalool synthase gene expression in the C. breweri flower’, Plant Cell, 8, pp. 1137–1148. Gallage, N.J., Esben‐Hansen, H., Kannangara, R., Olsen, C.K., Motawia, M.S., Jørgensen, K., Holme, I., Hebelstrup, K., Grisoni, M., & Møller, B.L. (2014). ‘Vanillin formation from ferulic acid in Vanilla planifolia is catalyzed by a single enzyme’, Nature Communications, 5, p. 4037 doi: 10.1038/ncomms5037.

Floral Essential Oils: Biosynthesis, Classification and Commercial Applications

King, A.J., Brown, G.D., Gilday, A.D., Larson, T.R., & Graham, I.A. (2014). ‘Production of bioactive diterpnoids in the euphorbiaceae depends on evolutionarily conserved gene clusters’, Plant cell, 26, pp. 3286–3298. Knudsen, J.T., Eriksson, R., Gershenzon, J., & Stahl, B. (2006). ‘Diversity and distribution of floral scent’, Botanical Reviews, 72, pp. 1–120. Lange, B.M. & Ghassemian, M. (2005). ‘Comprehensive post‐genomic data analysis approaches integrating biochemical pathway maps’, Phytochemisty, 66, pp. 413–451. Muhlemann, J.K., Maeda, H., Chang, C., Miguel, P.A., Baxter, I., Cooper, B., Perera, M.A., Nikolau, B.J., Vitek, O., Morgan, J.A., & Dudareva, N. (2012). ‘Developmental Changes in the Metabolic Network of Snapdragon Flowers’, PLoS ONE, 7,p: e40381. doi:10.1371/ journal.pone.0040381. Machumi, F., Samoylenko, V., Yenesew, A., Derese, S., Midiwo, J.O., Wiggers, F.T., Jacob, M.R., Tekwani, B.L., Khan, S.I., Walker, L.A., & Muhammad, I. (2010). Antimicrobial and antiparasitic abietane diterpenoids from the roots of Clerodendrum eriophyllum’, Natural Product Communications, 5, pp. 853–858. Nagegowda, D.A. (2010). Plant volatile terpenoid metabolism: ‘Biosynthetic genes, transcriptional regulation and subcellular compartmentation’, FEBS Letters, 584, pp. 2965–2973. Jeon, S., Kim, N., Koo, B., Kim, J., & Lee, A. (2009). ‘Lotus (Nelumbo nucifera) flower essential oil increased melanogenesis in normal human melanocytes’, Experimental & Molecular Medicine, 41, pp. 517–524. Tritsch, D., Hemmerlin, A., Bach, T.J., & Rohmer, M. (2010). ‘Plant isoprenoid biosynthesis via the MEP pathway: in vivo IPP/DMAPP ratio produced by (E)‐4‐hydroxy‐3‐ methylbut‐2‐enyl diphosphate reductase in tobacco BY‐2 cell cultures’, FEBS Letters, 584, pp.129–134. Tholl, D., Chen, F., Petri, J., Gershenzon, J., & Pichersky, E. (2005). ‘Two sesquiterpene synthases are responsible for the complex mixture of sesquiterpenes emitted from Arabidopsis flowers’, Plant Journal, 42, pp. 757–771.

Further Reading Canales, M., Hernández, T., Caballero, J., de Vivar, A.R., Avila, G., Duran, A., & Lira, R. (2005). ‘Informant consensus factor and antibacterial activity of the medicinal plants used by the people of San Rafael Coxcatlán, Puebla’, Méxican Journal of Ethnopharmacology, 97, pp. 429–439. Charles, D.J. (2012). Antioxidant Properties of Spices, Herbs and Other Sources, Springer. Chen, F., Tholl, D., D’ÕAuria, J.C., Farooq, A., Pichersky, E., & Gershenzon, J. (2003). ‘Biosynthesis and emission of terpenoid volatiles from Arabidopsis flowers’, Plant Cell, 15, pp. 481–494. Cseke, L.J., Kaufman, P.B., & Kirakosyan, A. (2007). ‘The Biology of Essential Oils in Pollination of Flowers’, Natural Products Communications, 2, pp. 1317–1336. Davies, K.L. & Turner, M.P. (2004). ‘Morphology of floral papillae in Maxillaria Ruiz & Pav. (Orchidaceae)’, Annals of Botany, 93, pp. 75–86. Koch, C., Reichling, J., Schneele, J., & Schnitzler, P. (2008). ‘Inhibitory effect of essential oils against herpes simplex virus type 2’, Phytomedicine, 15, pp. 15:71–78.

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Nagegowda, D.A., Gutensohn, M., Wilkerson, C.G., & Dudareva, N. (2008). ‘Two nearly identical terpene synthases catalyze the formation of nerolidol and linalool in snapdragon flowers’, Plant Journal, 55, pp. 224–239. Pateraki, I., Andersen‐Ranberg, J., Hamberger, B., Heskes, A.M., Martens, H.J., Zerbe, P., Bach, S.S., Møller, B.L., Bohlmann, J., & Hamberger, B. (2014). ‘Manoyl oxide (13R), the biosynthetic precursor of forskolin, is synthesized in specialized root cork cells in Coleus forskohlii’, Plant Physiology, 164, pp. 1222–1236. Sanganeria, S. & Vibrant, I. (2005). ‘Opportunities for flavor and fragrance industry’, Perfumer and Flavorist, 30, pp. 24–34. Wedge, D.E., Galindo, J.C.G., & Macías, F.A. (2000). ‘Fungicidal activity of natural and synthetic sesquiterpene lactone analogs’, Phytochemistry, 53, pp. 747–757.

Floral Essential Oils: Biosynthesis, Classification and Commercial Applications

Problems Chapter 11 1 Aromatic monoterpenoids in plants have two main functions either they attract pollinators or they provide defense against microbial pathogens and herbivores which find these molecules unpleasant and stay away from plants secreting them. Although grasses and roses belong to two different groups of flowering plants, that is, monocots and eudicots, but many of their fragrant molecules like geraniol and linalool are same. It shows that same metabolic pathways synthesize these aromatic molecules through mevalonate pathways, which take place within their plastids. Based upon this information, show steps involved in geraniol biosynthesis within plastids of (a) leaves of lemongrass (b) epidermal cells of the petal of a rose. 2 Plants with insectidical properties are used in making bioinsecticides. Use of many plants is becoming common in many mosquitoes and pesticidal sprays. Among them basil, lavender, rosemary, chinaberry and geranium are more noticeable. However, plants synthesize these molecules for their own defense against predators but they are also toxic for such plants and they use different strategies to protect them from toxic effects of such molecules. Explain different ways through which plants protect them from toxic effects of such molecules. 3 Menthol synthesis and secretion in mint plant is a part of its herbivory defense. Explain how menthol translocation to roots of mint protects them from insects. 4 Match plants in column A to their main essential oil in column B. Column A

Column B

Theol

Rice

Geraniol

Ginger

Zingiberone

Coffee

Linalool

Rose/Lemongrass

Oryzol

Coffee

Coffecol

Lemon

Limonene

Mint/Jasmine/Citrus

5 Volatile molecules are released through modified structures present in epidermal cells of leaves and flowers in order to attract their pollinators. However, once released in air through diffusion, they become part of atmospheric gases. Do you think that these molecules can again be taken up by plants? Give reasons to support your hypothesis. 6 Give reasons to explain how environmental and climatic factors cause change in the chemical composition of essential oils of the same plant species and give some solu­ tions to overcome problems associated with species which produce less essential oil due to a change in their habitat?

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7 Aromatic molecules from plants can influence your mood, efficiency, and health through aromatherapeutic techniques. Do you support it or not? Give reasons to support your answer. 8 Explain the principle of gas chromatography‐mass spectrometry for isolation and separation of fragrant molecules. 9 Fragrances have been part of tradition and culture of different countries throughout history. Give an account of use of aromatic plants in different countries. 10 Explain important factors in solid phase microextraction which determine success of this method. 11 How can tissue culture techniques and breeding techniques bring advancement in the perfume and cosmetic industries? 12 Bioengineered perfumes will be common in markets which are made through t­aking genes for mevalonate synthesis from flowering plants and introducing them in bacteria. How can this idea be helpful in preserving the biodiversity of the plant?

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12 Aromatic Molecules From Flowers in Perfume and Cosmetic Industries 12.1  Introduction and Overview of Perfume and Cosmetic Industries Perfume and cosmetics industries of world largely rely on many aromatic molecules and pigments synthesized by flowering plants. As explained in last chapter, many of these fragrant molecules are carbon and hydrogen containing molecules (isoprene units) which combine with other molecules in order to make a peculiar fragrance. They are composed of few carbon atoms which acquire kinetic energy and can evaporate in air. A  perfume may be defined as a mixture of aromatic molecules which are preserved in a fixative which can retains their fragrance. Aromatic molecules are extracted from plants through both traditional as well as modern techniques involving distillation methods, solvent extraction, enfleurage, ­maceration, supercritical CO2 method, headspace method, solid‐phase micro extraction (SPME), simultaneous distillation/extraction, distillation/absorption, accelerated solvent extraction, microwave extraction, a combination of spectrometric techniques and mass spectrometric techniques, or through gas chromatography/olfactometry (GC/O). After extraction, molecules are blended and mixed with other molecules in order to develop a desired fragrance and are finally preserved in a suitable solvent ­usually ethanol. Concentration of aromatic molecules, solvent and water determines whether it is a perfume, cologne or a toilette. Recently, some research has been successfully conducted by some biotechnological companies in forming genetically engineered aromatic microbes by incorporating genes for fragrance formation (genes from MEP pathway which takes place in plastids) from plants into bacteria. One of the main objective of making perfumes from these genetically engineered bacteria is to preserve plants biodiversity and also to develop a desired, modified and unique product within shorter period of time. World’s largest perfume markets are in Europe, Africa, Middle East Region, North America, Asia Pacific and South America. Main producers from emerging countries are Brazil, China, Egypt, Mexico, Guatemala and Indonesia. Largest companies are Givaudan and international flavours and fragrance, Firmenich and Symrise, Quest International, Takasago, T. Hasegawa, Sensient Technologies, Mastertaste, Danisco and Mane (Berger, 2007). Many publications like the Encyclopedia of Essential Oils by Gildemeister and Hoffmann in 1899 and the Theory of the Extraction and Separation of Essential Oils by way of Distillation, by Carl V. Rechenberg, in 1908, determined Flowering Plants: Structure and Industrial Products, First Edition. Aisha Saleem Khan. © 2017 John Wiley & Sons Ltd. Published 2017 by John Wiley & Sons Ltd.

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foundations of perfume industry. The European Pharmacopeia contains monograph on 25 essential oils. The United States is the world’s largest perfume market with annual sales of millions of dollars. However, many perfumes which are synthesized today are used in cosmetic products like soap bars and in make up and skin care products to make them fragrant. Asia‐Pacific market accounts only 6% of perfume industry (Jones, 2010). Ten major crops of world contribute to world’s major supply of essential oil.

12.2  History of Perfume Making The ability of plants to synthesize aromatic compounds and their release in air to ­communicate with the environment has fascinated humans since long ago. This has led to many attempts to preserve the nature of aromatic molecules not only for the aroma but also for healing purposes. Ancient perfumes were prepared by extracting essential oils from plants by pressing and steaming and oils which were then burned to make the air fragrant. In history of Greece, Egypt, Rome and other Arabian countries, perfumes have been a symbol of beauty, art, attraction, love, spiritualism and religious rituals. Many myths and beliefs are associated with the use of perfume throughout the history. Their use is also representative of culture, tradition and civilization of different regions of world. The concept of using perfumes or aromatic plants was also based on a myth that Aphrodite, goddess of beauty and love was the first one to use perfume. Alexander the Great, sent home shipments of spices, incense and perfume‐making plants while he conquered Arabia. Greek are believed to be first manufacturer of perfumes through distillation process and prepared perfumes through steeping of aromatic plants in hot and cold oils. Greek and Romans used to take daily baths and this ritual included use of many perfumes and aromatic plants. Theophrastus (371–287 B.C.) wrote about many aromatic plants. Dioscorides (c. 40–90 C.E.) wrote about perfume recipes during the time of Nero. Use of perfume and attar was also part of Islamic culture. Al‐Kindi, a Muslim Arab philosopher, for the first time described the formation of pure distilled alcohol from wine distillation. He wrote about recipes of fragrant oils and aromatic perfume water in his book Kimiya‐al‐Itr (Book of the Chemistry of Perfume). Later, Avicenna discovered process of extraction of essential oils and fragrances. Egyptians used perfumes in their temples as an offering to their Gods. Perfumery was used for oriental art until the healing effects of perfumes were discovered through Europeans in the seventeenth century (Figure 12.1). Due to the antiseptic and germicidal nature of many aromatic molecules, like cloves and cinnamon, they were used by doctors while treating patients suffering from plague. The French king, Louis XIV, was called the Perfume King, due to his court decorated with floral aromatic pavilion, and dried flowers placed in bowls throughout the palace to freshen the air. Royal guests were given baths in rose petals. However, in England, the use of perfume was common in lockets and canes for sniffing. Mughal Queen Noor Jahan used to sail in a canal filled with rose water with great Moghul. Iban Chaldun reported that in the eighth and in ninth centuries, roses were traded to India and China. Rose industry developed in the tenth to seventeenth century in Persia, and spread over to India, Austria and North Africa. Roses were introduced in Bulgaria by Turks.

Aromatic Molecules From Flowers in Perfume and Cosmetic Industries

Figure 12.1  Egyptian scene depicting the preparation of lily perfume, fourth century B.C.

First synthetic perfume was nitrobenzene, made from nitric acid and benzene to scent the soaps with almond like smell. Citronellol, an alcohol with rose‐like odor, was created in the U.S. by Francis Despard Dodge. In 1925, the stronger smelling ethyl vanillin which does not occur naturally, was used to create another synthetic perfumer, Shalimar. Culturally, perfume bottles were crafted in Europe, Egypt and Venice.

12.3  Aromatic Flowers, Leaves and Woods Used in Perfumery Although flowers are the main aromatic part of flowering plants but leaves of many plants are also aromatic and therefore used in perfume making as well as in cosmetic products. Common aromatic leaves used by perfume industries include lavender, patchouli, sage, violets, rosemary and citrus leaves. Tomato and hay leaves are used for their green fragrance they add to perfumes. Resins like labdanum are also utilized in making perfumes. Fruits of lemon, orange, litsea, juniper berry and vanilla are aromatic but apples, strawberries and cherries do not yield significant odors and mostly their flavours are synthetic. Seeds of tonka beans, coriander, cocoa, nutmeg, and anise are also aromatic. Flowers of rose, jasmine, frangipani, lavender, narcissus, lilies, linage, geranium, magnolia, marigolds, moonflower, ocimum, chamomile, lemongrass, vetiver, violets, vanilla, rosemary, citrus, cannabis flower, wallflowers, and iris are used in making of perfumes. Well‐known aromatic plant families include Apiaceae, Asteraceae, Lamiaceae, Lauraceae, Myrtaceae, Piperaceae, Rutaceae, Santalaceae, Zingiberaceae and Zygophyllaceae. Popular essential oils used in making of perfume include geraniol, linalool, agar oil, basil oil, bergamot oil, cardamom oil, frankincense oil, grapefruit oil, jasmine oil, and patchouli oil (Figure 12.2).

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(a)

(b)

(c)

(d)

Figure 12.2  (a‐d) Essential oil of: (a) Rosa spp. and (b) Jasminum spp. exhibit a wide range of antimicrobial activities and also used in perfumery, (c) Cestrum spp. contain complex mixture of α‐pinene, camphene, myrcene, α‐phellandrene, α‐terpinene, phellandrene and β‐ocimene, linalool and fenchol, (d) oil secretory structures in epidermal peel of Citrus spp.

Roses are widely used in perfumery due to their stable fragrance and oriental nature. They can blend well with any floral group. Rose absolute from R. damascena and R. centifolia is prepared by steam‐based solvent extraction from rose flowers, however later is cheaper and commonly used for making rose solutes. Use of rose water from rose oil is common in Asian countries. Rose oil is obtained through hydrosteam and hydrodistillation of rose flowers in 0.025 to 0.030% yield. Almost 3500 to 4000 kg of flowers make one kg of rose oil.

12.4  Traditional and Modern Techniques of Distillation and Isolation of Fragrant Molecules Advancement in analytical techniques and in biotechnological sciences is producing modified and unique products of commercial importance not only in pharmaceuticals, food, textile, beverage industries, but also in cosmetic and perfume industries. Today, modern techniques have developed more reliable and efficient methods for extraction of aromatic molecules from plants which retain their original nature in products. Many of these methods are environmental friendly and produce products which are not ­hazardous for environment. Essential oils are extracted through steam distillation, hydrodistillation or through water distillation. Distillation parameters which are standardized include distillation length, steam pressure, temperature and packing of plants in distillation stills. After

Aromatic Molecules From Flowers in Perfume and Cosmetic Industries

distillation, essential oils are refined and marketed for industries. World’s demand of essential oils is 100,000 to 110,000 tonnes out of which 4344 tonnes is utilized by perfume industry, 80410 tonnes for processing, and 217670 tonnes for flavors ­ (Sanganeria, 2005). Perfume oil is diluted with solvent, whereas undiluted oils are composed of high ­concentrations of volatile compounds. Ethanol or mixture of ethanol and water are used as a medium. However, sometimes dilutions are done with jojoba, fractionated coconut oil or wax. Extraction of essential oils from plants requires the following steps: 12.4.1  Collection & Extraction of Essential Oils are Prerequisite Steps in Traditional Perfume Making

Extraction of essential oils from aromatic parts involves prerequisite in perfume m ­ aking. Steam is passed through the samples in a container which converts essential oil into gas. Gas is then passed through the tubes, cooled and then liquified. Oils can also be extracted by boiling the petals of aromatic plants in water instead of streaming them. However, temperature of steam should be maintained in a way that, it is ideal for heat‐ sensitive fragrant molecules and do not change their nature. In steam distillation method, live steam is injected under pressure upto 7kg/cm2. This method is more ­efficient and yields higher yield, however it is not suitable for delicate flowers. 12.4.2  Enfleurage & Maceration Through Grease and Fats

In enfleurage, flowers are spread on glass sheets coated with thin layer of grease, which are further supported by wooden frames in tiers. Many wooden frames are sandwiched one above the other separated by layers of fat. Flowers are removed through hand and are continuously replaced until the grease absorbs considerable amount of fragrance. This method is used for flowers like jasmine and tuberose (Figure 12.3). In maceration, warm fats are used at 60–70°C instead of grease to absorb flower smell. Fat can be separated from flowers and can be re‐used for fresh flowers. Grease or fats are further dissolved in alcohol to obtain the essential oil. However, fats used should be saturated and odorless in order to make sure that they do not transfer their aroma to extracts. 12.4.3  Solvent Extraction Convert Aromatic Molecules in Concrete and Absolute

During solvent extraction, flowers are placed in large rotating containers or drums and benzene or petroleum ether is poured over them to extract fragrant molecules. It results in the formation of waxy material or concrete which is composed of oil. The waxy material is highly fragrant, composed of long‐lasting aromatic compounds. Aromatic oils are extracted from waxy concrete with ethyl alcohol. After the removal of ethyl alcohol, remaining material is called an absolute which makes the concentrated form of natural fragrances. When burnt off, it leaves a higher concentration of oil on the bottom. After the extraction of desired essential oils, perfumes are blended by an expert called nose. A mixture of different fragrances is required in many cases to develop a certain fragrance and this may take even years to develop a perfume formula. Once scent is approved by expert, it is mixed with alcohol. However, amount of alcohol may vary

291

Plant essential oil based cosmetic and food products

Cinnamol

Eucalyptol

Geraniol

Limonene

Linalool

Citronellol

Farnesol

Eugenol

Essential oils

Wooden frame holding glass sheet

Greasy glass sheet with floral bed

Perfumes

Cosmetic products

Food products

Collection & harvest Solvent extraction Enfleurage

Solvent extraction

Maceration Distillation Multitray for extraction

Blending

Top Note xxxx

Middle Note Base Note

EAU DE COLOGNE

EAU DE TOILETTE

10–20% perfume oil in alcohol

3–5% perfume in alcohol and water

EAU DE PARFUM less than 2% perfume

Figure 12.3  Essential oils are widely used in perfume and in cosmetic products. Different steps of extraction of essential oil in making perfumes involve enfleurage in which flowers are spread on glass sheets coated with thin layer of grease or solvent extraction in which flowers are placed in large rotating drums and benzene or petroleum ether is used to extract fragrant molecules. This is followed by formation of fragrant waxy material or concrete which is composed of oil. Ethyl alcohol is removed and remaining material is called an absolute which makes the concentrated form of natural fragrances. Essential oils are blended and diluted with water or ethanol. Eau de perfumes have 10–20% of essential oils, eau de cologne is composed of 3–5% of perfume in alcohol or in water, whereas eau de toilette contains less than 2% of perfume.

Aromatic Molecules From Flowers in Perfume and Cosmetic Industries

according to perfume. Perfumes having higher concentration of essential oils are ­generally expensive than perfumes with low amount of essential oils. In expression or cold press, fruit is manually pressed to remove essential oil, that is, citrus oil is separated from rind using this old method. A combination of essential oils and watery components are produced through this process which produce essential oils after separation. However, main disadvantage of this method is that it does not produce pure essential oils and they oxidize if not refrigerated. Many cold press oil machines are used for making industrially important products within few minutes. They maintain high temperature, pressure and continuous conditions. Infrared temperature control system is used to control the pressing temperature and moisture. They are used for pressing sunflower, tea seed, cottonseed, pepper seeds, walnuts, castor, almonds and other oil crops widely. Another method head‐space analysis is also used to isolate fragrant molecules. This method makes use of glass bell jars which is placed over plant. The glass jar is composed of material which absorb odors from plants by acting as a trap to collect fragrant ­molecules. It grabs air in the jar and can also be used for re‐creating or associating ­fragrances with location from where they are collected (Figure 12.4). However, the head‐space method is replaced by a better and less time‐consuming method, that is, SPME which actually maintains the originality of aromatic compounds in the gas phase above a product. It facilitates analytical detection of olfactory impression which can be perceived by the nose. It is a solvent‐free sample extraction technique which is used to concentrate flavors and fragrances in a shorter period of time. This method is based on developing an equilibrium between sample which is in liquid or gas phase and in stationary phase which is a silica microfiber coated with a polymer film, followed by thermal desorbing of concentrated compounds through the injecting of gas chromatograph which is transferred to capillary column. Thickness and coating of fiber, concentration, time and temperature for desorption are important factors in SPME. Due to reliability of this method it is widely used in many industries and also for analyzing spice flavor in food industries. Headspace method

Inverted jar containing absorbent for trapping odors Fragrant molecules

Floral bed

Figure 12.4  Isolation of essential oils using the head‐space method. Plant material are placed in an inverted jar which contains absorbent for trapping odors of fragrant parts of a plant.

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Solvent‐assisted flavor evaporation (SAFE) is another reliable method for extraction of aroma compounds from food which produces high yields of polar flavor substances and produces high quality aromatic molecules without changing their nature. It is used in commercially sold grapefruit juice and soft drinks. 12.4.4  Eau De Parfum, Eau De Toilette and Eau De Cologne

Many perfumes, colognes and toilettes are available in market which can be distinguished from each other on the basis of their fragrance and duration that how longer they can be smelled. It is actually the ratio of alcohol and perfume oil which differentiates perfume from eau de toilette and eau de cologne. Most of the perfumes are ­composed of 10–20% perfume oil dissolved in alcohol and sometimes are composed of a negligible amount of water. Cologne constituents include 3–5% oil diluted in 80–90% alcohol and 10% of water. Toilette are more diluted ones with less than 2% of perfume oil which is dissolved in 60–80% alcohol and 20% water. Attars are distillates from flowers collected with sandalwood oil. 12.4.5  Perfume Notes

Perfumes were entirely based on natural molecules from plants until 1880, however, Aime Guerlain in 1889, introduced the concept of perfume notes. Each perfume or essential oil comes with three notes, that is, top note or notes de tete, middle or notes de coeur and bottom notes or notes de fond. These notes are indications of their fragrances. Top notes are associated with citrus‐like smells. Middle notes give an indication that aromatic sources of perfumes are rose and jasmine. However, base notes show woody fragrances. Top notes are perceived immediately, middle or central notes emerge just prior to when top notes dissipate, whereas base notes appear almost half an hour after the departure of middle notes. Many perfumes reflect aspects of different families. Even perfumes claimed as single floret have undertone of other fragrances. However, true or unitary perfumes are not common as it requires perfumes to exist as only singular aromatic. Ambery perfumes consist of fragrances from vanilla, along with fragrance from other flowers and wood, which are further modified by camphorous oils, and incense resins. They remind of Victorian Era imagery of Middle East and Far East. Woody fragrances are dominated by woody scents of sandalwood, cedar and patchouli. However, leathery are synthesized from scents of honey, tobacco, wood and wood tars.

12.5 CO2 as a Solvent to Extract Fragrant Molecules in Super‐critical CO2 Fluid Extraction Method As mentioned in Chapter 9, CO2 is used as an ideal organic solvent to isolate fragrant molecules and to extract flavors from spices due to its chemical stability and nonflammable nature and low critical point (Figure 12.5). If higher pressure is applied during extraction of oils, it results in formation of thicker and waxier material, which constitutes plants compounds as well as essential oil. It is known as total. However, lower

Aromatic Molecules From Flowers in Perfume and Cosmetic Industries

32° C Supercritical fluid Liquid phase

Solid phase

Critical point

7.4 MPa

Gas phase Pressure

Triple state

Temperature

Figure 12.5  Phase diagram (p, V) for a pure compound in a close system. The triple point indicates the critical pressure and temperature of carbon dioxide (Capuzzo et al., 2003).

pressure produces select which is composed of only essential oils. Super‐critical CO2 extraction method is proved to be more efficient in extracting essential oils from many different parts because volatile compounds extracted though this method maintain their organoleptic properties. Major parameters in involved in this method are temperature, pressure and flow rate. Main steps involved include extraction, separation, and CO2 recovery. Plant is charged into the extractor, along with the CO2 which is introduced into the extractor through a high‐pressure pump (>74bar) and CO2 heater (>31 °C). The extract laden CO2 is sent to a separator through a pressure reduction valve. At reduced temperature and pressure, the extract precipitates in the separator, whereas the CO2, free of extract, is recycled to the CO2 main tank (Figure 12.6). Modern supercritical extraction machines make use of ultrasonic effect to enhance the mechanical action of essential oil extract. Applications of supercritical CO2 machines also extend to herbal extraction of wide variety of a Chinese herbs. They are equipped with dynamic extraction and concentration unit attached with water separator and efficient condenser. Supercritical fluid extraction is very efficient and widely used in products like foods and flavors, pharmaceuticals and nutraceuticals due to its mild and gentle extraction conditions which maintain the original flavor of food constituent and original aromatic nature of molecules. It is commonly used for decaffeination of extraction of essential oils, oleoresins and aromas from spices.This method is also efficient in removing residual organic solvents or impurities like pesticides from main food ingredients. It is also used for processing of tobacco, hops, spices, fats and oils and in cosmetic, leather, textile and paints and beverages.

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(g) (f)

(h) Condenser (gaseous)

(e)

(d)

CO2 storage tank (liquid)

(Liquid gaseous)CO2

(Separator extract)

(Extractor E2)

(Extractor E1)

Floral extract

(a)

CO2 Heater (31°C) (Supercritical)

(Liquid) Pressure controlling pump >74

(Condenser liquid)

(c)

(b)

Figure 12.6  (a‐e) Supercritical CO2 method is one of the reliable and efficient method used for making perfumes: (a) CO2 (liquid) is passed through condenser, (b) Pressure of flow is maintained by pump, (c) CO2 heater converts CO2 in supercritical form, (d‐e) CO2 in its supercritical form enters extraction vessels (E1 and E2), (f) It is followed by separation of volatiles from liquid CO2 in a separation vessel, (g) CO2 recovery as gaseous state in a condenser, (h) storage in a tank. (See insert for color representation of the figure).

12.6  Modern Perfume Making Machines Modern perfume‐making machines have originated from France. They are composed of stainless steel heat preservation freezing tank with titanium metal coiled pipe and microscopic filtration films. Stainless steel acts as a moveable supporter. These machines have sealing type electric control system which is provided with sanitary pipe fittings and valves. Nowadays electric fragrance oil machines are used to make commercially important essential oils which uses an essential oil distillator suitable for extracting essential oil and hydrosols from plants such as such as lavender, rosemary, pine and fir needles, peppermint and eucalyptus leaves. Main applications of products are extraction of essential oils and aromatherapy products stores. Almost 220V (options of 3000W, 5000W) electricity is used to form steam which is transferred to the bottom of a distillation still in which two layers of steam for re‐use and extraction of approximately 1.2 L per degree of electricity consumption are made (Figure 12.7).

12.7  Aromatherapy: Relaxation Through Aromatic Molecules Although aromatherapy has a broad meaning but it can best explained as a ‘branch of herbal medicine which involves use of different parts of aromatic plants for relaxation of mind, body as well as soul in order to bring peace, harmony and balance in life’.

Aromatic Molecules From Flowers in Perfume and Cosmetic Industries

(a)

(b)

Figure 12.7  Supercritical CO2 machines.

Aromatic molecules from plants may serve for humans to know more about their inner self, to develop a bond between man and nature and also to clean soul which is reflected through a positive behavior towards life and people. It can be used as a psychological treatment by psychiatrists as well as for medical doctors. Although aromatherapy is widely practiced in many countries as a part of ancient civilization, unfortunately until now there has not been sufficient evidence which reports its increase its applications in medical sciences although in some countries like France, aromatherapy is practiced by chemists and medical doctors. Aromatic plants have been used since long ago for making the air fragrant, making aromatic solutions and also for healing purposes. Hippocrates, the Greek physician first developed methodical system for aromatherapy. Archaeological evidences from tomb engravings, stones, clay tablets have shown that use of aromatic plants as perfumes, for cooking, bathing, for magic‐religious rituals and for aromatherapy was very popular in

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Egypt, Mesopotamia, Babylonia and in India. Fennel, garlic and cumin were used as ancient recipes by physicians and as a part of folk medicine. Myrrh and frankincense were associated with religious activities and considered to be sacred. Aromatic plants were also used in embalming of mummies in Egypt in order to preserve corpses from decay. They were also used in ancient medicinal treatments in form of juices, infusions, decoctions and poultices. Egyptian remedy kyphi was prepared through 16 different ingredients for various uses as medicines, incense, perfume, and as sedatives. Discovery of clay distillation unit from an ancient city Taxila in Pakistan indicated that oils were extracted from aromatic plants, however, distillation process was introduced by Avicenna or Ibn Sena who practiced a medical system known as Unani Tibb which was based on ancient system of Hippocrates and Galen. Aromatic wood of Cinnamomum camphor, Santalum album and cedar are used for  many religious rituals in many countries of world due to their essential oils for ­aromatherapy. Lavender oil, rose oil, rosemary, jasmine, daisies, eucalyptus and citrus spp. are commonly used plants for aromatherapy. However, some oils may also be ­poisonous due to their high ketone contents. Many of them have therapeutic effects, like antiseptic, analgesic, antinflammatory, antimicrobial, stimulants and relaxants. They can be inhaled when applied externally on skin, or may be applied through ­massage. Many health problems like anxiety, depression, insomnia, headache and ­muscular pains can be relieved through aromatherapy. Rose flowers are widely used in aromatherapy due to their pleasant and peaceful ­fragrances which is a mixture of almost 300 volatile essential oils. Two species of roses are mainly grown due to their fragrances, that is, R. damascena and R. centifolia. R. damascena is also known commonly as damask rose. It is grown in Bulgaria, Turkey and China. R. centifolia or cabbage red is grown in Morocco, France and Egypt. Major rose oil producing countries are Bulgaria, Iran, Turkey, Morocco and China. Main fragrant volatiles of roses are β‐damascenone, β‐damascone, β‐ionine and rose oxides which are responsible for 90% fragrance of rose flowers. In addition, other ­compounds in rose oils are citronellol, geraniol, nerol, linalool, phenyl ethyl alcohol, farnesol, stearoptene, α‐pinene, β‐pinene, α‐terpinene, limonene, p‐cymene, ­camphene, β‐caryophyllene, neral, citronellyl acetate, geranyl acetate, neryl acetate, eugenol, methyl eugenol, rose oxides, α‐damascenone, β‐damascenone, benzyl alcohol, rhodinyl acetate, β‐ionone, and phenyl ethyl formate. Modern aromatherapeutic techniques involves direct application of aromatic essential oils or plant‐based cosmetic products in the form of massage creams, lotions, moisturizers in spas and in beauty salons. It is also reported that sniffing rosemary can increase a person’s memory but scientific studies to support this hypothesis are still missing.

12.8  Cosmetic Industry: An Overview and History Plants are known to be used in herbal home‐made remedies and in many cosmetic products since long ago. Historical evidences have shown that cosmetic products were used by Egyptians and ancient Greeks many years ago. Egyptians used eye makeup and cosmetics around 3500 B.C.E. Use of hair dyes and makeup for eyes and cheeks became common in Rome in 100 C.E. (Willett, 2010).

Aromatic Molecules From Flowers in Perfume and Cosmetic Industries

Cosmetics is a broad term which includes all skin and body care products including lotions, creams, sun‐blocks, massage creams, scrubs, facial masks, lip balms, foundations, toners, face wash, cleansers, age controlling creams, blush, mascaras, eye liners, kajals, hair care products like hair oil, shampoos and hand‐care products like nail p ­ olish, and lipsticks. In 1879, Procter and Gamble introduced ivory soap for hygiene purposes. Avon Brand developed in 1886 as California Perfume Company. It was followed by foundation of many well‐known companies which used plants as their major products. The Pure Food and Drug Act allowed federal government to regulate cosmetic industry in 1906. French chemist Eugene Schuller developed the first commercial hair color product and this led to foundation of the company L’Or’eal. Beauty tycoon Elizabeth Arden opened her first salon on New York’s Fifth Avenue in 1908. Max Factor foundation was developed for film artists in 1914. Camay soap was introduced in 1926 by Proctor and Gamble. In 1932, Revlon company was founded and a year after later, Este’e Lauder was developed which is one of the prominent twentieth‐ century in cosmetic industries. Use of animals for testing of cosmetic products, regarding whether they are safer to use, was initiated in 1933 in the United States, as a result of an incident in which eyelash‐darkening treatment, Lash Lure, made a woman blind. The Food and Drug Administration (FDA) regulated the Federal Food, Drug and Cosmetic Act to provide safety against hazardous chemicals in 1938 in cosmetic products. An international company, Beauty Without Cruelty (BWC) was formed in support of animals used for testing cosmetic products in 1959. Anita Roddick, developed friendly cosmetics and skin care business Body Shop in Great Britain in 1976. FDA banned 27 harmful ingredients in shampoo products in 1990. The concept of using bacteria in cosmetic products originated in 2002 when the U.S. FDA approved use of Botox, which is a derivative of Botulinum bacterium. It is used for anti‐wrinkle cosmetic treatment due to its paralyzing effect on facial muscles which otherwise form wrinkles around the eyes and forehead. The European Union banned animal testing in cosmetic products in 2009. However, L’O’real which is one of the world’s largest cosmetic industry and other companies like Avon, Clinique, Este’e Lauder, and Body Shop made a strong protest against animal testing. Cell cultures, donated eye tissues and computer modeling are suggested as an alternatives to animal testing. It is estimated that people all over the world spend $330 billions on cosmetics each year, among which France and Japan spend over $230 per capita on an annual basis. Americans and Germans spend over $173 and $154 respectively. In America, it is one of the most profitable businesses after pharmaceutical and software industries. New York and Paris are known to be symbols of beauty. Over $230 per capita are spent by France and Japan on beauty products (Jones, 2010). Only L’Oreal and P&G contribute over one fifth of total world’s sale. In 2008, Avon is worth $11.3 billion. However, Dove by Unilever, and Pantene by P &G earned sales of $5.3 billions and $4.5 billion respectively. China also makes the world’s fourth largest market for cosmetic products. L’Oreal by Paris, is one of the world’s largest cosmetic industry known for its cosmetic products and introduced over 500 products. Other popular industries used world wide are Olay, Ponds, Keihls, Neutrogena, Dove, Nivea, Estee Lauder, Clinique, Proctor, Maybelline, Rimmel, Lancome, and Gamble, and Unilever.

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12.9  Popular Plants and Their Products in Cosmetic Products Essential oils of many plants are used in skin care products for cleansing, moisturizing, steaming, facial scrubs and masks. Many of them are extracted from chamomile, lavender, roses, jasmine, daffodils, daisies, lemon, orange and patchouli. Citronellal, geraniol, citronellol, and geranyl acetate from C. winterianus and C. nardus have value in beauty products. Oils of lemon, lavender, mint and sage control oil levels of oily skin. Rosemary, lemon, and verbena oil are used for dry skin. For acne, lavender, sage, chamomile and geranium, patchouli are commonly used. R. damascena, synthesize citronellol, geraniol, nerol and linalool. Essential oil of lemongrass and roses are widely used in cosmetics and fragrances. Flowers of Michelia champaka are commonly used in many perfumes and cosmetic products due to presence of cineole and isoeugenol as active components. Leaf twigs of Eucalyptus citriodora are source of citronellal, citronellol, cineole and iso‐pulegol that make an important part of many cosmetic products. Patchouli Pogostemon spp. synthesize patchoulinol and caryophyllene in the leaf twigs which are also used in cosmetic products. Flowers of Tagetes erecta yield beauty and aromatic products due to molecules like tagetone, linalool, limonene, linalyl acetate (Figure  12.8). Farnesol and geraniol from flowers of Polyanthes tuberosa are also popular in cosmetic industries. Almost 34% of materials used by L’Oreal are plant based products. (a)

(b)

(c)

(d)

Figure 12.8  Plants which are commonly used in many cosmetic products: (a & b) Marigolds and daisies are known to be used in over 200 cosmetic formulations including creams, shampoos and lotions. Their main activity is due to presence of many triterpene alcohols, triterpene saponins, flavonoids and carotenoids, (c & d) Tagetes spp. contain beauty molecules like tagetone, linalool, limonene and linalyl acetate.

Aromatic Molecules From Flowers in Perfume and Cosmetic Industries

12.10  Anti‐Aging Properties of Some Plants and Their Applications in Cosmetic Products Plant stem cells do not undergo aging process due to their hormones like auxins and gibberellins. Some research is focusing on the use of stem cells from plant meristems containing these phytohormones in anti‐aging products in order to delay process of aging. Novacell plant stem cell anti‐aging night cream is made from meristem cells of Vigna radiata (mung beans). They are rich in many anti‐oxidants and provide protection to plants against UV radiations. These creams are not tested on animals and therefore 100% cruelty free products. Although many anti‐aging skin care products are available in market, however, plant stem cells‐based cosmetic products are rare. Turmeric (Curcuma longa) is an ancient plant which has been used since 4000 years ago by folklore and in many traditional remedies by Asian and African countries. It is a perennial herb and its rhizome is used as a powder which is a popular spice flavor in Asian cuisine. Medicinal and anti‐aging properties of turmeric are due to group of cucurminoids of rhizomes. It prevents aging of skin due to inhibition of matrix metalloproteinase‐2 expression (MMP‐2) which is responsible for aging process. Curcumin administration also increases activities of oxidative defense system and extend the life span of Drosophila melanogaster through modulation of expression of aging genes (Lee et al., 2010). Flower extract of M. grandiflora is known to decrease the melanin content in B16F10 melanoma cells, which indicate the potential use of plant in skin care ­products. It is also reported to protect skin photo‐aging by inhibiting NF‐ kappaB ­transcription (Lim et al., 2014). Many polyphenols and polysaccharides of C. sinensis contribute to age‐defying properties (Povichit et al., 2010) more than vitamin C and E. Most common polyphenols are epicatechin, epicatechin‐3‐gallate, epigallocatechin‐3‐gallate, theanine and caffeine. Many anti‐oxidants in tea have skin rejuvenation potential which are reported to improve redox imbalance due to senescence in cardiac tissues of aged rats. Pomegranates also have strong activity on preventing collagen degradation by suppressing the expression of matrix metalloproteinase in osteoarthritis patients (Ahmed et al., 2005). Pomegranate rind extract possesses skin‐whitening activity due to its effects on inhibition of melanocyte proliferation and melanin synthesis by tyrosinase in melanocytes. Pomegranate also promotes production of collagen and elastin due to presence of many antioxidants in its fruits and in flowers. Major part of skin is made up of collagen fibers which give tensile strength to skin while elasticity is provided by elastin fibers and glycoaminoglycan which keeps skin hydrated. They are produced by fibroblasts which produce wrinkles and pigmentation when they become aged. Phytochemicals from plants can inhibit activities of collagenases and elastases due to flavonoids, phenolics and tannins. They also inhibit activity of collagenases from Clostridium histolyticum (ChC) which degrades extracellular matrix of skin (Thring et al., 2009). Leaf extract of Camellia japonica is also used in anti‐aging cosmetics due to its inhibitory effect on expression of collagenase MMP‐1 in human fibroblast cells. A. vera is also know to improve skin fibroblast and accelerates the collagen production process. Therefore it is being used in many skin care products like scrubs, face polishers and other cosmetic products, due to its anti‐aging potential. Aloe leaf gel is

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used to rejuvenate and to tone skin in many commercial skin products. Aloin, a brown gel of aloe is a used as sunscreening factor in many skin care products (Figure 12.9). Leaf extract of billberry are known to have inhibitory activities on collagenase and elastase enzymes which causes ragging and wrinkled skins. They also reduce melanin contents in B16 melanoma cells and therefore are being used in skin whitening and anti‐aging creams (Table 12.1). Many skin care anti‐aging products of Loreal, Geraniol, Olay and Aesop are composed of plant molecules including linalool, limonene, caffeine, geraniol, citronellol, tocopherol which are known to have anti‐aging activities. Oil of Olay was introduced in 1949 by Graham Wulff with skin‐healing abilities which was followed by formation of many anti‐aging creams by Lancome and Este’e Lauder. Cosmetic industries market anti‐aging skin care treatments known as cosmeceuticals more than any other product containing UV‐protection anti‐aging factor. FDA has also approved use of Botox as a substitute to cosmetic surgery due to its anti‐aging properties.

12.11  Bioengineered Aromatic Bacteria With Lemon and Rose Fragrances Introduction of metabolic pathways involved in the formation of aromatic molecules in microorganisms like bacteria by taking genes from plants is an emerging trend which has led to formation of fragrant bacteria which can be widely used as natural insecticidal and pesticidal products in agricultural and perfume industries. Formation of ­fragrant microorganisms can save plants biodiversity and can also free up land used for plant crops for their uses in food and pharmaceutical products, which is more important rather than in perfume and cosmetic products. This also minimizes the risks and other natural factors which are related with plant growth as sometimes yield is not enough due to natural factors in order to meet demand of industries. Concept of making aromatic microbes originated in 2010 due to shortage of patchouli plant which is widely used as fragrance in incense sticks and health care products due to climatic conditions. Biotech companies like Allylix, Isobionics, Givaudan, Firmenich, Evolva, and International Flavors and Fragrances produce microbial‐based perfume. Valencene is a commonly used microbial‐based perfumes. It is naturally found in orange peel of Valencia orange (Bomgardner, 2012; Gupta et al., 2015). Metabolically engineered microbes can produce linalool, nerolidol and patchoulol. Givaudan has patented a microbial biosynthetic pathway for vanillin synthesis. Now genes for aromatic s­ hikimic acid pathway are also engineered in bacteria. In addition to microbial fermentation and tissue culture, scientists are developing methods to genetically engineer microorganisms in order to produce fragrant molecules like geraniol, linalool and menthol. E.coli is also being genetically engineered to produce zingiberone by a group of biologists at Kent University. They are forming genes of interest and submitting them to I GEM HQ to add it to repository, making iGEM database of genes and functional products known as biobricks. These scientists are also making further efforts to introduce gene for mevalonate pathway in bacteria (which lack this pathway) for terpenoid biosynthesis through transformation with plasmid pBbA5c‐MevT‐MBIS5 containing genes encoding mevalonate pathway (Figures 12.10 & 12.11).

(a) A. vera extract in form of a gel

Aloin Polysaccharides Amino Acids Anthraquinone

Rejuvenating molecules

Fibroblast skin cells

Aloe Vera plant

A. vera rejuvenating cream

Deep Wrinkles

Inhibits action of MMP-1 (matrix metalloproteinases), collagenase, elastase enzymes which causes wrinkles

(b) Young skin

(c) Old skin

(d-e) Rejuvinating skin

Collagen fibers give strength to the skin

MMP-1 (matrix metalloproteinases), collagenase, elastase enzymes causes wrinkles

Molecules from A.vera make skin firm by inhibiting action of aging enzymes & form collagen fibers

Figure 12.9  (a‐e) A. vera is used in many anti‐aging products due to its ability to strengthen collagen fibers of skin and in improving fibroblast cell structure. It is due to inhibitory effects on collagenase and elastase enzymes and MMP‐1 (matrix metalloproteinases) which can cause wrinkles on skin. (a) Aloe gel or aloin in leaves has wound healing properties due to its effects on rapid maturation of collagen. It is used as sunscreening factor in skin care products, (b) section through normal skin, (c) wrinkled skin, (d‐e) recovery with A. vera anti‐aging cream.

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Table 12.1  Plants with anti‐aging properties and some products.

Plant

Family

Main molecules with anti‐aging effects

Aloe spp.

Aloaceae

aloin

Aloe vera stem cell antiaging cream Novacell Plant stem cell antiaging night cream (nutraceutical solution)

Camillea spp.

Theaceae

Catechins, phenolic compounds, tannins

Camillea nut facial hydrating cream Camillea antiaging serum Camellia anti‐aging skin butter

Lavandula spp.

Lamiaceae

limonene, α‐pinene, β‐farnesene, geraniol, borneol, lavendulol

Cotswold Lavender Daily moisturizer Lavendula oil Face wash Pure nature Blueberry and Lavender extract calming face cream Lavender body yoghurt

Rosa spp.

Rosaceae

citronellol, geraniol, linalool, limonene, β‐ionine, rose oxides, farnesol, stearoptene, α‐pinene, β‐pinene, β‐caryophyllene

Rose water Rosa face mask Rose hip facial moisturizer Rose day cream

Products

Genes sequence for terpene synthases genes encoding zingiberone synthase and l­inalool synthase from Sorghum bicolor and lavender are introduced in plasmid for expression in bacteria to produce fragrant bacteria. Genes for limonene synthase are also being introduced in plasmids to produce bacteria with lemon smell. Bacteria living in roots of vetiver play an important role in determining the composition of fragrance oil. Therefore researchers are working to modify oil’s structure through microbes to promote production of essential oil and to also change the chemical structure of oil by giving it different flavors. It may also increase their use in bioinsecticides due to their insectidical properties. In fact, vetiver it is only grass which is mainly cultivated due to its root essential oils. Solid state fermentation is also being used as a technique to p ­ roduce aromatic microbial metabolites in large quantities.

Plasmid with genes (c) encoding MVA pathway

(b)

MVA pathway

MVA pathway

(a) Cell of petal of Rosa sp.

Geraniol Limonene Linalool Citronellol

(d) E coli.

Aromatic gene inserted in E coli.

(e) Bioengineered perfume

Figure 12.10  (a‐e) Steps in making of genetically engineered aromatic bacteria: (a) Cell of petal of Rosa sp., (b) Genes for MVA pathway which forms volatile molecules from plants like roses are incorporated in plasmids, (c) Transformed plasmids are incorporated in bacteria like E. coli, (d) Transgenic E. coli with MVA pathway, (e) Aromatic bacteria are used in making perfumes, cosmetics and pesticides in order to minimize use of plants for making perfumes and cosmetic products. (See insert for color representation of the figure.)

Hey! “look, I have got new genes. I am fragrant now.”

“Don’t worry now because of this guy, the people will not harm us for making their products” “Let him be happy”

Hey! “he stole our genes”

“He is no more our friend. Let’s go”

Figure 12.11  Cartoon illustration of transgenic E. coli with geraniol to be used in different products like perfumes.

Aromatic Molecules From Flowers in Perfume and Cosmetic Industries

12.12  Future Considerations Due to the success in formation of perfumes containing bioengineered aromatic bacteria, it is now possible to develop aromatic bacterial perfumes which can be used as insecticides and pesticides. Therefore, biotechnologists should focus on introduction of bacterial‐based biopesticides in the market. There is a need to form pleasant perfumes with anti‐microbial and anti‐viral attributes which can protect us from disease‐causing microbes when we spray them. Hazardous skin chemicals banned by FDA which cause skin cancer and allergies should be totally replaced by safe chemicals in all cosmetic products. Concept of green chemistry and ecorespectful chemicals need to be promoted. Although, it is a big challenge for industries to go green, therefore there is a need to explore further biochemical nature of plants in order to replace harmful chemicals with natural producers in cosmetic products (without compromising on their biodiversity). Further, use of plants need to be restricted to food, agriculture, and pharmaceutical products instead of using them in making perfumes or adding fragrance to cosmetic products, so we depend upon plants only for necessities and not for luxury in order to preserve our natural biodiversity.

References Ahmed, S., Wang, N., Hafeez, B.B., Cheruvu, V.K., & Haqqi, T.M. (2005). ‘Punica granatum L. extract inhibits IL‐1beta‐induced expression of matrix metalloproteinases by inhibiting the activation of MAP kinases and NF‐kappa B in human chondrocytes in‐vitro’, Nutrition, 135, pp. 2096–2102. Berger, R.G. (2007). Flavours and Fragrances: Chemistry, Bioprocessing and Sustainability, Springer. Bomgardner, M.M. (2012). ‘The Sweet Smell of Microbes’, Chemical and Engineering News, 90, pp. 25–29. Capuzzo, A., Maffei, M.E., & Occhipinti, A. (2013). ‘Supercritical Fluid Extraction of Plant Flavors and Fragrances’, Molecules, 18, pp. 7194–7238. Gupta, C., Prakash, D., & Gupta, S. (2015). ‘A Biotechnological Approach to Microbial Based Perfumes and Flavours’, Journal of Microbiology & Experimentation, 2, pp. 1–8. DOI: 10.15406/jmen.2015.01.00034. Jones, G. (2010). Beauty imagined: A History of the Global Beauty Industry, Oxford University Press Inc., New York. Lee, K.S., Lee, B.S., Semnani, S., Avanesian, A., Um, C.Y., Jeon, H.G., Seong, K.M., Yu, K., Min, K.J., & Jafari, M. (2010). ‘Curcumin extends life span, improves health span, and modulates the expression of age‐associated aging genes in Drosophila melanogaster’, Rejuvenation Research, 13, pp. 531–570. Lim, T. (2014). Edible medicinal and non‐medicinal plants: Flowers, 8, Springer. Thring, T.S., Hili, P., & Naughton, D.P. (2009). ‘Anti‐collagenase, anti‐elastase and anti‐ oxidant activities of extracts from 21 plants’, BMC Complementary and Alternative Medicine, 9, p. 27. DOI: 10.1186/1472‐6882‐9‐27 Povichit, N., Phrutivorapongkul, A., Suttajit, M., Chaiyasut C., & Leelapornpisid, P. (2010). ‘Phenolic content and in vitro inhibitory effects on oxidation and protein glycation of

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some Thai medicinal plants’, Pakistan Journal of Pharmaceutical Sciences, 23, pp. 403–408. Sanganeria, S. (2005). Fragrance, Flavours & Essential Oils, Ultra International Limited, Vibrant India. Willett, J.A. (2010). The American Beauty Industry Encyclopedia. Greenwood.

Further Reading Arora, D., Rani, A., & Sharma, A. (2013). ‘A review on phytochemistry and ethnopharmacological aspects of genus Calendula’, Pharmacognosy Reviews, 7, pp. 179–187. Kaiser, R. (1991). In Perfumes, Art, Science, and Technology. In: Muller P.M., and Lamparsky. D (ed.). Elsevier, Amsterdam, p. 213. Marsili, R. (2010). Flavor, Fragrance and Odor Analysis, Marcel Dekker. Pitman, V. (2004). Aromatherapy: A Practical Approach, Nelson Thornes Ltd. Rozenbaumm, H.F., Patitucci, M.L., Antunes, O.A.C., & Pereira, N. (2006). ‘Production of aromas and fragrances through microbial oxidation of monoterpenes’, Brazilian Journal of Chemical Engineering, 23, pp. 273–279. Singh, O., Khanam, Z., Misra, N., & Srivastava, M.K. (2011). ‘Chamomile (Marticaria chamomilla L.): An overview’, Pharmacognosy Reviews, 5, pp. 82–95. Sumiyoshi, M, & Kimura, Y. (2009). ‘Effects of a turmeric extract (Curcuma longa) on chronic ultraviolet B irradiation‐induced skin damage in melanin‐possessing hairless mice’, Phytomedicine, 16, pp. 1137–1143. Yoshimura, M., Watanabe, Y., Kasai, K., Yamakoshi, J., & Koga, T. (2005). ‘Inhibitory effect of an ellagic acid‐rich pomegranate extract on tyrosinase activity and ultraviolet‐induced pigmentation’, Bioscience, Biotechnology and Biomedicine, 69, pp. 2368–2373.

Aromatic Molecules From Flowers in Perfume and Cosmetic Industries

Problems Chapter 12 1 Explain medicinal, pharmaceuticals and aromatic nature of following molecules by filling spaces in the columns. Also give example of one plant which synthesizes these molecules.

Aromatic molecules

Pharma­ ceuticals

In storage of food products

Cosmetic products

Perfumes

Biopesticides and Insectides

Examples

Zingiberone Linalool Lemonene Nerol Citronellol Coffecol Curcumin Safrole Vanillin Caryophyllene Eugenol Isoeugenol Menthol Geraniol 2 What advantages does the supercritical CO2 method for extraction of essential oils provide over other methods for extraction of essential oils? 3 Which plants are commonly used as anti‐aging ingredients in cosmetic industries. Explain the mechanisms through which anti‐aging molecules from these plants can reduce wrinkle and melanin formation in skin fibroblasts. 4 Give example of some phytochemicals in tea which have anti‐aging properties. 5 Differentiate between the following: i. enfleurage and maceration ii. SPME and SAFE iii. eau de perfume and eau de perfume cologne iv. concrete and absolute v. headspace analysis and cold expression vi. ambery and woody fragrances vii. top notes and middle notes 6 Genetically engineered bacteria with the smell of ginger and lemon are produced by a group of scientists by expressing genes for zingiberone synthase and linalool synthase from Sorghum and lavender. This results in the introduction of mevalonate

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acid pathway (MVA) in bacteria which is largely responsible for formation of ­aromatic molecules in plants. Similarly many genetically engineered bacteria are capable of producing linalool, nerolidol and patchoulinol. A Do you think that aromatic molecules in these bacteria can serve the same purposes as natural aromatic molecules from plants? Or are they safe to be used for food and pharmaceutical products? Propose different ways through which genetically engineered aromatic bacteria can be used as biopesticides. B Show the process of binary fission in an aromatic bacteria with genes of MVA expressed from lemon.  7 What is the concept of ecorespectful cosmetics? What efforts can you do to ­promote the use of ‘green cosmetics’ among your community?  8 What is solvent‐assisted flavor evaporation method (SAFE)? Explain its applications.  9 Sunflower family (asteraceae) is composed of many genera which are commonly used in making of many cosmetic products. Examples include calendula, chamomile and daisies. A Give for any five plants in family asteraceae which can be used in making ­cosmetics and perfumes B Explain the uses of chamomile in cosmetic products. 10 Daisies produce a wide variety of aromatic molecules which are used to add ­fragrance to many cosmetics products. Given below is flower of daisy; give examples of any five molecules which are biosynthsized by daisies within plastids of their petal cells in the figure below.

311

Glossary A Absolute:  A mixture of essential oils produced during solvent extraction without ethyl alcohol. Age‐related macular degeneration (AMD):  Degeneration of the part of the retina related to the controlling of vision due to aging process. Alkaloids:  Defensive nitrogen‐containing secondary metabolites which give bitter taste to plants. Allelochemicals:  Chemicals released by plants to inhibit growth of neighboring plants. Amphitropous:  Ovules with curved nucellus on both sides. Anatropous:  Ovules with micropyle adjacent to funiculus. Androecium:  Collective term for stamens or male flowers. Angiosperms:  One of the abundant group of plants also known as flowering plants with ovules enclosed in ovary and endosperm as nutritive tissue around embryo. Angiosperms phylogeny group:  Modern system of classification based on facts from molecular phylogenetics. Antenna pigments:  Light‐absorbing pigments in chloroplasts which act as antenna. Anthocyanins:  Flavonoid pigments which give pink, blue, purple or red color to plant organs. Anthocyanoplasts:  Anthocyanins‐storing bodies in vacuoles of some plants. Antipodal cells:  A group of three cells towards the chalazal end of ovules of embryo sac. Apomorphies:  Also known as derived traits; distinguishing character of a species and its descendants. Aromatherapy:  Application of fragrant essential oils from plants to relieve from stress and to stimulate brain. Adenosine triphosphate (ATP):  Energy currency of cell synthesized within m­itochondria or chloroplasts which acts as a coenzyme. ATP Binding cassettes (ABC):  Protein transporters of one of the largest gene superfamily, essential extra or intracellular transport of molecules. ATP synthase:  Enzyme in mitochondria and chloroplast which produces energy in form of ATP. Avon:  American international cosmetic company. Flowering Plants: Structure and Industrial Products, First Edition. Aisha Saleem Khan. © 2017 John Wiley & Sons Ltd. Published 2017 by John Wiley & Sons Ltd.

312

  Glossary

B Basal angiosperms:  Group of flowering plants composed of only a few species which diverged from lineage towards monocots and eudicots. Bast fibers:  Supporting fibers of phloem. Bicollateral vascular bundles:  Vascular bundles having phloem on both sides of xylem. Body Shop:  British cosmetic company known for skin care products. Botox:  Drug from bacteria Clostridium botilinum used for anti‐wrinkle treatment. Bottom notes:  Main theme of perfume fragrance which lasts for longer after evaporation of top and middle notes. Bryophytes:  Non‐vascular plants which reproduce through spores and do not produce seeds or flowers.

C Caleosins:  Calcium‐binding proteins associated with oleosomes. Callose:  Plant polysaccharide synthesized by enzyme callose synthase located on cell wall. Calvin cycle:  Light independent cyclic pathway in stroma of chloroplasts which depends upon products of light reactions, that is, ATP and NADPH. Calyx:  Outermost protective whorl of many flowers also known as sepal. Campylotropous:  Partially inverted ovule in which micropyle is close to funiculus. Cardenolides:  Toxic steroids in plants which are defensive against herbivores. Carnations:  Ornamental spp. of Dianthus which are popular in floriculture. Carotenes:  Deoxygenated fat‐soluble pigments in plants which give them orange, yellow and red shades and important in photosynthesis. Carotenoids:  A large group of fat‐soluble plant pigments synthesized within plastids with 40 carbons. Cell suspension culture:  Also known as cell culture. Multiplication of cells in suspended liquid medium through agitation. Cellulose:  Cell wall polysaccharide of glucose molecules composed of β‐1,4 linkage. Chalaza:  Part of ovule opposite to micropyle. Channels:  Passive membrane transporters on biological membranes with low substrate specificity. Chromosomes:  Thread like structures of nucleic acids which bear genetic information in form of genes. Cisternae:  Flattened membranes of Golgi bodies and endoplasmic reticulum. Cladogram:  A diagram of evolutionary relationships within a group of related organisms which share common ancestors. Closed system of venation:  Venation of leaves without free veinlets. Cold press:  Removal of essential oil from citrus fruits through manual press. Collateral vascular bundles:  Phloem surrounding xylem either on upper side or on lower side. Collenchyma:  Supporting parenchyma with uneven thickenings of pectin and cellulose on cell wall.

Glossary

Concrete:  Fragrant waxy material produced from aromatic plants during solvent extraction. Connective:  Vascular supply of anthers. Core angiosperms:  Main group of angiosperms composed of monocots and core eudicots. Corolla:  Petals of flowers. Cosmetic:  Beauty products for skin and body care, health and hygiene. Cristae:  Folds of inner membrane of a mitochondrion. Cryopreservation:  Preservation at low temperature which inhibits germination of seeds. Cyanogenic glycosides:  Sugar containing secondary metabolites which release HCN. Cytoskeleton:  Network of microtubules and actin filaments which gives support to cell. Cytosol:  Main fluid of cell in which enzymes and organelles are suspended. Site for metabolic activities of cell.

D DNA:  Double‐stranded nucleic acid which carries genetic information. Double fertilization:  Fertilization of embryo sac with two sperm nuclei. A characteristics of flowering plants.

E Eau de Cologne:  Perfume from Cologne, Germany containing almost 3–5% of essential oils. Eau de parfum:  Perfume with 10–20% of essential oils. Eau de parfume:  Perfume with less than 2% of essential oils. Ecorespectful cosmetics:  Cosmetic products based on concept of green chemistry, friendly with environment, renewable and safer to use. Egg apparatus:  Group of three cells in embryo sac of angiosperms containing egg cells and associated synergids. Elaiophores:  Oil‐releasing epidermal cells. Embryo sac:  Female gametophyte also known as embryo sac which contains egg cells with synergids and antipodal cells present opposite to egg cell. Endergonic:  Energy depending reactions which produce products of higher energy. Endoplasmic reticulum:  Network of tubules in connection with nuclear membrane with or without ribosomes. Endosperm:  Nutritive tissue of embryo within seeds of flowering plants. Endothecium:  Inner layer within walls of anthers. Enfleurage:  Extraction of essential oils and perfumes from flowers through odorless animals or vegetable fats. Epidermis:  Outermost layer surrounding all plant organs. Essential oils:  Mixture of volatile atoms synthesized by plants to attract pollinators or to repel pathogens.

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  Glossary

Este’e Lauder:  American cosmetic company. Eudicots:  Also known as true dicots. Angiosperms having monophyletic origin and tricolpate pollens. Exergonic:  Energy‐utilizing reactions within cells which produce products of low energy. Extrafloral nectar:  Nectar from any part of plant except flowers.

F Fibers:  Sclerenchyma with long and tapering ends. Flavonoids:  A group of polyphenols pigments which attract pollinators. Floral nectar:  Nectar synthesized by flowers. Floriculture:  Branch of horticulture which deals with ornamental flowers for gardens and floristry. Florigene:  Australian biotech company which produces novel color of flowers through genetic modification. Food and Drug Administration (FDA):  Federal agency of U.S which deals with legal introduction of foods and drugs in markets. Fragrant bacteria:  Genetically engineered bacteria with genes of fragrance formation from plants. Funiculus:  Vascular supply of ovule through stalk at base of ovule.

G Gametophyte:  Gametes‐producing phase in life cycle of angiosperms which is usually haploid. Gas chromatography:  Technique in analytical chemistry which uses gas as a moving carrier medium and used for isolation and identification of compounds. Genetic engineering:  Process of producing desired products or desired organisms through modification of genetic material. Genomics:  Branch of genetics which deals with genetic make of individuals. Glycolysis:  Series of reactions in cytosol of cells of almost living organisms which breakdown glucose in order to release energy and to form important intermediates required by cell. Glycosides:  Sugar‐containing molecule attached with functional group through glycosidic bond. Glyoxysomes:  Specialized peroxisomes in which breakdown of fatty acids take place. Golgi apparatus:  System of vesicles and folded membranes involved in modification and transport of molecules‐like proteins. Granum:  Stacked membrane structure in chloroplasts composed of an aggregate of thylakoids and site of light reactions. Green textile:  Plant‐derived environment friendly fabrics. Gymnosperms:  Group of seed‐producing plants with ovules not enclosed in ovary. Gynoecium:  Collective term for carpels or female part of flower.

Glossary

L Laticifers:  Latex‐containing cells or vessels. Light harvesting complex:  Aggregate of antenna proteins and pigments on thylakoid membrane involved in transfer of energy from light to reaction center. Lignin:  Aromatic polymers in cell wall of xylem and fibers covalently attached with cellulose. Lipton:  A tea brand by Unilever and Pepsico. Loreal:  A French cosmetic company. Lytic vacuoles:  Vacuoles with hydrolytic enzymes and involved in detoxification of harmful and waste molecules.

M Matrix:  Fluid of a mitochondrion which is the site of many important metabolic activities like citric acid cycle. Mass spectrometry:  Analytical technique which isolates and characterizes molecules according to their mass to charge ratio. Multidrug and toxin extrusion proteins (MATE):  Protein transporters in plants related with transport of many secondary metabolites. MEP (Methylerythritol pathway):  Non‐mevalonate pathway in plastids which synthesizes volatile terpenoids. Maceration:  Extraction of essential oils through warm fats. Metabolomics:  Comprehensive qualitative and quantitative analysis of small molecules within a cell to give better understanding of cell biology and physiology. Metaxylem:  Xylem which differentiates after protoxylem. Micropyle:  Opening of embryo sac towards egg cell which ruptures when pollen tube enters. Microsporangium:  Sporangium which forms male gametophyte and contains microspores or pollens. Microsporocytes:  Cells which produce microspores after meiosis. Microwave assisted extraction:  Extraction of essential oils through microwave. Mid‐vein:  Main vascular supply composed of xylem and phloem. Middle lamellae:  Cementing material of cell wall. Middle notes:  Perfume fragrance which appears after top notes dissipate. Mitochondria:  Organelles in which biochemical respiration takes place. It provides energy to cell due to presence of enzyme ATPsynthase. Monocots:  Group of flowering plants which are mostly herbs, with parallel venation of leaves, scattered vascular bundles and have seeds with one cotyledons. Monophyletic:  A group of organisms having a common ancestor. Monoterpenoids:  Volatile terpenoids having two isoprene units (C10H16).

N NADH (Nicotinamide adenine dinucleotide):  Coenzyme in living cells. NADPH (Nicotinamide adenine dinucleotide phosphate):  Cofactor used in many anabolic reactions and provides energy almost equal to three molecules of ATP.

315

316

  Glossary

Nectar:  Nutrient‐rich fluid produced by nectaries of plants to attract pollinators. Nectar guides:  Visible or invisible patterns on petals of many flowers to guide insects towards hidden nectar. They are visible under UV light. Nectaries:  Nectar‐producing tissue. Nestle:  Swiss international food and beverage company after the name of Swiss chemist Henri Nestle in 1867. Neurotransmitters:  Chemical messengers which communicate between brain and body. Nucellus:  Central part of ovule containing embryo sac. Nucleotides:  Building blocks of DNA‐containing nucleosides linked with p­hosphate group. Nucleus:  Organelle containing DNA and RNA.

O Olay:  American cosmetic company, a brand of Procter and Gamble’. Oleosomes:  Spherical organelles which are storage site of triacylglycerols and mostly found in seeds and pollens of many angiosperms. Opiates:  Drug derived from opium. Osmophores:  Fragrance releasing glands on epidermal cells.

P Parallel venation:  Veins of almost equal length which run parallel along the leaf lamina of many monocots. Parenchyma:  Ground tissue of plants which is composed of actively dividing thin cells and site of metabolic activities. Pentose phosphate pathway:  A series of reactions which use phosphorylated glucose to synthesize lignin, deoxyribose, ribose, cambium and phenolic compounds. Perforation plate:  End plates in xylem vessels through which they xylem cells are connected and transport water molecules. Perfume:  Mixture of fragrant molecules preserved in a medium. Perfume notes:  Different elements of a perfume which give different fragrances and appear in order of top, middle and bottom notes. Perianth:  Sepals and petals of flowers. Peroxisomes:  Single membrane‐bounded organelles responsible for oxidative reactions and involved in detoxification of many waste products. Phloem:  Food‐conducting tissue of plants. Photolysis:  Breakdown of water in presence of light which leads to flow of protons towards ATPsynthase and flow of electrons towards electron transport chain carriers on thylakoid membrane. Pit aperture:  An opening on inner surface of secondary cell wall where lignin is not deposited.

Glossary

Pith:  Central part of stem made up of parenchyma cells. Plasma membrane:  Lipid bilayer structure with proteins which is present next to cell wall and which regulates movement of molecules in and out of cells. Plasmodesmata:  Passages in cell walls of plants for transport of molecules. They are formed by smooth endoplasmic reticulum. Plastids:  Double membrane organelles in plant cells, chloroplasts, chromoplasts, leucoplasts and amyloplasts. Platoglobuli:  Plastids of plants cells containing chromoplasts in form of droplets. Polar nuclei:  Two haploid nuclei in the center of embryo sacs of female gametophytes. Primary plasmodesmata:  Extensions of smooth endoplasmic reticulum in the form of tubelike opening, lined by plasma membrane. They develop during cell division. Procambium:  Meristematic tissue which forms primary xylem and primary phloem. Protoxylem:  First developed xylem with narrow vessels. Psychoactive:  Drug which can alter mental state. Pteridophytes:  Vascular spore producing plants like ferns.

R Reaction center:  Pair of chlorophyll ‘a’ molecules in photosystem where photoylsis takes place due to presence of specific proteins. Relaxed selection:  Reduction in morphological structures like perches in some flowers due to absence of pollinating birds. Replication:  Formation of two identical molecules of DNA from parent DNA. Reticulate venation:  Web‐like network of veins found in leaves of many eudicots. Revlon:  American cosmetic company. Ribosomes:  Small particles are composed of RNA and proteins which help in protein synthesis. RNA (Ribonucleic acid):  Single‐stranded nucleic acid involved in protein synthesis.

S Saponins:  Glycosides with foaming characteristics. Sclerenchyma:  Supporting tissues, that is, fibers or sclereids with lignified thick walls. Secondary cell wall:  Cell wall between primary cell wall and plasma membrane. Secondary metabolites:  Defensive molecules in plants produced during primary metabolism. Also known as plant functional or natural products. Secondary plasmodesmata:  Branched plasmodesmata which develop during cell expansion. Shikimic acid pathway:  Pathway which links metabolism of carbohydrates to formation of amino acids and lignin. Sieve areas:  Areas in wall of sieve tube members through which transport of m­olecules takes place.

317

318

  Glossary

Sieve tube members:  Carbohydrates and nutrients conducting cells of phloem in angiosperms. Sieve plate:  Areas where phloem cells are connected and transport of molecules takes place. Sporophyte:  Spore‐producing phase in the life cycle of angiosperms which is dominant. Starbucks:  American coffee company and coffeehouse chain. Steam distillation:  Steam‐based separation process for extraction of less‐volatile essential oils. Steroleosin:  Sterol‐binding oil bodies. Storage vacuoles:  Main vacuoles storing water, pigments and nutrients. Stroma:  Fluid of chloroplast and site of Calvin cycle. Supercritical CO2:  Fluid form of CO2 above its critical temperature and pressure. Synergids:  Associated cells of egg apparatus of embryo sac which guide pollen tube to egg cell for fertilization.

T Tannins:  Polymers of phenolic compounds which give yellow or brown color. Tannosomes:  Tannin containing organelles. Tapetum:  Nutritive tissue within anthers which provide nutrition to developing pollens. Tassel:  Pollen‐bearing flowers in plants like corns. Tepals:  Sepals and petals of monocots which are combined and cannot be differentiated. Terpenoids:  Secondary metabolites containing isoprene units (C5H8). Thylakoid:  Membrane‐bound compartments in chloroplasts which are the site of light reactions due to the presence of antenna pigments and proteins. Tissue culture:  Development of an organism in artificial medium from living cells. Tissues:  A group of cells with similar metabolic activities. Tonoplast intrinsic proteins:  Aquaporins in vacuolar membrane of seeds. Top notes:  Perfume fragrances which can be smelled immediately after spray. Tracheids:  Water‐conducting cells of xylems with elongated tapering ends. Transcription:  Formation of mRNA from DNA. Transgenic:  A genetically modified organism due to incorporation of genes from other organism. Translation:  Protein synthesis in cytosol from ribosomes and RNAs. Translocators:  Proteins on biological membranes which form pores for transport of molecules. Transmission tissue:  Tissue which provides nutrition and supports growth of developing pollen tube through style. Transmission tissue specific proteins:  Act as an attractant for the growth of pollen tube. Trichomes:  Epidermal outgrowths of leaves or flowers which may be defensive and secretory. Tricolpate:  Pollens with three grooves or furrows and characteristics of eudicots.

Glossary

V Vacuole:  Water and pigments storing organelle which degrades toxic compounds and maintains turgidity of a plant cell. Vascular cambium:  A lateral meristem found only in eudicots. Vessels:  Water‐conducting cells of xylem with spiral, reticulate, annular or helical thickenings of lignin.

X Xanthophylls:  Oxygen‐containing carotenoids which give yellow color to fruits, pollens, leaves and petals. Xylary fibers:  Fibers found in wood and originate from vascular cambium Xylem:  Water and mineral conducting tissue of plants.

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321

Index a Absolute, 291 Acetyl‐CoA, 34f Aconitine, 215, 228, 233 Acyclic, 263 Adenosine diphosphate (ADP), 138f, 139 Adenosine triphosphate (ATP), 138f, 139 ADP‐glucose phosphorylase, 246 Age‐related macular degeneration, 204 Ajmaline, 228 Alkaloids, 32f, 33 Allelochemicals, 214, 272 Alpha‐carotene, 197 Amphitropous, 93 Anandamine, 227 Anatropous, 93 Androecium, 78 Angiosperms Phylogeny Group, 2 Annual carnations, 252 Antenna pigments, 143, 144f Anther, 92f, 93 Antheraxanthin, 192f Anthocyanin(s), 15, 36f, 161 Anthocyanin biosynthesis, 166f, 167f Anthocyanoplasts, 15 Anti‐aging, 301–302, 303f, 304t Anti‐cellulite, 231, 236 Antipodals, 93 Apocarotenoids, 192f Aquaporins, 69 Aromatherapy, 296 Astaxanthin, 192f Asterids, 3, 78f Astrosclereids, 59, 61f

ATP binding cassettes (ABC), 14, 99 ATP synthase, 138f Atropine, 228 Attar, 294 Attention deficit disorder, 228 Auraxanthin, 192f Aurones, 35, 36f Avon, 299

b Basal angiosperms, 2–3, 78f Base note, 292f Bast fibers, 57 Benzoxazinoids, 42 Berberine, 228 Beta‐carotene, 192f, 197 Betalains, 36f, 181 Bicyclic, 263 Biobricks, 302 Bioenergy crops, 65 Bioengineered bacteria, 302, 305f Bioengineered terpenoids, 281 Biquinate, 235 Black tea, 226 Border carnations, 252 Bordered pits, 64f Botulinum, 299 Brachysclereids, 59 Bryophytes, 1

c Cacao beans, 227, 229f Caffeine, 213 Caffeine biosynthesis, 219, 220f

Flowering Plants: Structure and Industrial Products, First Edition. Aisha Saleem Khan. © 2017 John Wiley & Sons Ltd. Published 2017 by John Wiley & Sons Ltd.

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Index

Caffeine extraction, 225f Caffeine synthase, 220f, 221f Caleosins, 19 Callose, 69 Calvin cycle, 144f Campylotropous, 93 Cannabinoids, 40f Capsaicin, 200–202, 201f Capsanthin, 192f Capsorubin, 192f Caramelization, 224 Carbonization, 224 Cardioactive glycosides, 37 Carnation, 241, 250–255 CarotenAll, 204, 206f Carotene, 36f Carotenoid(s), 17, 36f, 136f, 190–191, 198f Carotenoid biosynthesis, 193, 194f, 195f, 196f Carotenoids in pollen, 197, 198, 198f, 199 Carpel, 87–88, 91f Carriers, 20 Caryophyllene, 272 Caryopsis, 96 Cell suspension culture, 42f Chalaza, 90 Chalcones, 35, 36f Channels, 19, 20, 21f, 98–99, 101f Chocolatl, 227 Cisternae, 15 Cladogram, 2, 4f Cocaine, 216, 234 Codeine, 234 Coffecol, 224 Cola nut, 223 Collenchyma, 53, 57 Commelinids, 3 Companion cell, 69 Conching, 228, 229f Concrete, 291 Condensed tannins, 17 Convolvulin, 216 Core angiosperms, 2, 78f Cosmeceuticals, 302 Cosmetic, 270f, 287, 299 Cotton bolls, 57 Coupled transport, 21 Criollo, 227

Cristae, 13 Cryopreservation, 255 Curare, 215 Cyanidin, 165, 166f Cyanogenic glycosides, 37 Cyryptoxanthin, 192f Cysteine‐rich proteins (CRP), 124 Cytoskeleton, 7, 10

d Delphinidin, 165, 166f, 248f Deo‐perfume, 271 1‐Deoxy‐D‐xylulose‐5‐phosphate (DOXP), 267f Deoxygenated carotenoids, 190 Dicots, 2 Dioecious, 107 Diterpenoids, 263, 265f, 274 Double fertilization, 124, 125 F Dove, 299 DOXP see 1‐Deoxy‐D‐xylulose‐5‐phosphate (DOXP) Dry method, 223 Dye‐sensitized solar cell, 179f, 181

e Eau de cologne, 292f, 294 Eau de perfum, 292f Eau de toilette, 292f, 294 Ecorespectful cosmetic, 307 Egg apparatus, 93 Elaiophores, 55, 79 Elizabeth Ardon, 299 Embryo sac, 93 Endergonic, 62, 137 Endosperm, 2 Enfleurage, 291, 292f Environment friendly, 290 Environment Protection Agency (EPA), 250 Essential oil, 261, 263t, 264t, 269f, 290 Este’e Lauder, 299 Excedrine, 232f Exergonic, 137 Exocarp, 151 Extracellular matrix, 120, 121f Extrafloral nectaries, 241 Extraxylarly cortical fibers, 57

Index

f

h

Farnesol, 272 Female gametophyte, 92f Fermentation, 227, 229f Fertilization, 124, 125f Fibers, 57–59 Filament, 92f, 93 Filiform sclereids, 59 Flavandiols, 35, 36f Flavones, 35, 36f Flavonoids, 35, 38f Flavonols, 35, 36f Floral nectary, 245f Floriculture, 247–248 Florigene Moondust, 254 Flying ointments, 215 Food and Drug Administration, 250, 299 Food colors, 200f Food vaccines, 230 Forastero, 227 Fourier Transform Infrared Spectroscopy (FTIR), 45 Fragrant bacteria, 302, 305f, 306f Friendly cosmetics, 299 Functional products, 31 Funiculus, 90

Half‐bordered pits, 66 Headspace method, 293 Heart shaped embryo, 126f Heroin, 216 Hollow style, 120, 121f H+ pumps, 22 Hydrolyzed tannin, 36f Hyperforin, 276 Hypericin, 276

g Gametophyte, 108 Gamma‐aminobutyric acid (GABA), 107 Gas Chromatography, 43f, 45 Gates, 19 Gene expression, 15, 140f Genetic biofortification, 205 Geraniol, 267f, 270–271, 306f Ghazaniaxanthin, 192f Gibberellic acid, 275 Globular shaped embryo, 126f Glycolysis, 32 Glycosides, 37, 39f Grana, 16 Green perfume, 289 Green tea, 214, 226 Guarana, 223 Gymnosperms, 2 Gynoecium, 78

i Insecticidal, 272, 273 Integuments, 90 Intercellular communication, 20f Inter membrane space, 13, 138f Intracellular communication, 19, 20f, 21f Intramarginal veins, 62, 62f Iridoids, 216 Isopentenyl pyrophosphate, 276 Isoprene, 263

k Karyogamy, 124 Keihls, 299 Kernel, 96 Kolatin, 223

l Lateral nectaries, 244f Layering, 224 Leaf disc method, 231f Leucoplasts, 200 Libriform fibers, 57 Ligandin transport, 168 Light harvesting complex (LHC), 143, 144f Light reaction, 143, 144f Lignification, 65 Linalool, 266, 269f, 270f Lipton, 226 Locule, 122f L‘O’real, 299 Luteins, 191f, 192f, 199, 206f Lycopene, 192f Lytic vacuoles, 14

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324

Index

m Maceration, 291, 292f Macrosclereids, 59 Macular pigments, 204 Magnoliids, 2 Male gametophyte, 92f Malvidin, 165 Margo, 66 Mass Spectrometry, 43f, 45 Matrix, 13 Matrix metalloproteinase, 301, 303f Maybelline, 299 Median nectaries, 244f Medox, 179f, 180 Menthol, 268f Mescaline, 215 Metabolomics, 44 Metaxylem, 62 Methylerythritol‐4‐phosphate (MEP), 217 Mevalonate pathway (MPA), 262, 276, 277f, 305f Mevalonic acid pathway, 34f Microencapsulation, 181 Microgametophyte, 94 Micropropagation, 255 Micropsore, 94 Micropyle, 90 Microspore mother cell, 94 Microsporocytes, 93 Microwave‐assisted simultaneous extraction, 44f Middle lamella, 10 Middle note, 292f, 294 Mitochondria, 13 Monocots, 2, 78f Monoecious, 107 Monophyletic, 2 Monoterpenoid indole alkaloids, 216 Monoterpenoids, 263, 265f Morphine, 234–235 Multidrug resistant transport proteins (MRP), 168

n Naringin, 165 Natural products, 31 Nectar, 243–245

Nectar guides, 14, 242, 244f Nectaries, 88, 241–242 Nectarin, 242, 246 Nectar robbing, 245 Nectar secretion, 245, 246f Nectary, 242 Neoxanthin, 192f Neurotransmitters, 216 Nicotine, 68f, 235 Nivea, 299 N‐methyltransferases, 222 Nose, 291 Nucellus, 90 Nuclear magnetic resonance, 45 Nucleotides, 16 Nutracuetical, 203

o Olay, 299 Oleoresin, 275 Oleosins, 19 Oleosome, 32f Oolong tea, 226 Opiates, 234 Optiberry extract, 181 Organoleptic, 295 Orthotropous, 93 Osmophores, 79 Osteosclereids, 59 Ovary, 88, 121f Ovule, 90, 91f Oxygenated carotenoids, 190

p Para‐Caff, 232f Parallel venation, 63 Parenchyma, 53, 55, 56f Pelargonidin, 165, 166f Pentose phosphate pathway (PPP), 141, 142f Peonidin, 165 Perfect, 78 Perforation plates, 63, 64f Perfume, 287 Perianth, 77 Petals, 77, 81, 82f, 87 Petals carotenoids, 200f Petunidin, 165

Index

Phloem, 69 Phloem proteins, 69 Phloem sap, 71 Photolysis, 143, 144f Photoprotective pigments, 199 Physiologically functional food, 230 Phytoene, 193 Phytofloral, 205 Pistillate, 78 Pit(s), 64f Pit aperture, 64f, 66 Pit membranes, 63, 64f, 66 Pit pairs, 66 Placenta, 90 Plant tissues, 53, 54f Plasmodesmata, 11 Plasmogamy, 124 Plastoglobuli, 193, 196 Polar nuclei, 93 Pollen tube, 120, 122f, 123–124 Polylactic acid fibers, 59, 60 Portisins, 180 Primary cell wall, 10 Primary plasmodesmata, 11, 12f Proanthocyanins, 35, 36f Proctor and Gamble, 299 Protoxylem, 62 Psychoactive, 215 Pteridophytes, 1–2 P type pumps, 22 Pumps, 19, 21f, 22 Pyrethin, 272

q Qahwa, 222 Quinalan, 235 Quinidex, 235 Quinidine, 228 Quinine, 235

r Reaction center, 143, 144f Receptacle, 88 Red Bull, 223 Relaxed selection, 85 Revlon, 299 Rosids, 3, 78f

s Saponins, 37, 39 Sclereids, 57, 59 Sclerenchyma, 53, 56f, 57, 58f Secondary cell wall, 10 Secondary metabolites, 31, 32f Secondary plasmodesmata, 11, 12f Secondary veins, 62 Select, 295 Semisolid style, 120, 121f Sepals, 77, 79, 80f, 150 Septum, 122f Sesquiterpenoids, 263, 265f, 272 Sieve elements, 69 Sieve plates, 69 Sieve pores, 69 Sieve tube member, 70 Solid Phase Microextraction, 45 Solid state fermentation, 304 Solid style, 120, 121f Solvent‐assisted flavor expression (SAFE), 294 Soma, 215 Sperm cell, 94, 127 Spikelets, 3, 95 Sporophyte, 108 Stamen, 92f, 93–95 Staminate, 78 Starch synthase, 246 Steam distillation, 45f, 269f Steroleosin, 19 Stigma, 88, 90f, 91f, 111, 116–117 Stimulants, 216 Storage vacuoles, 14 Stroma, 17 Style, 88, 119–120, 121f Supercritical CO2, 224, 225f, 294, 295f, 296, 297f SWEET, 72, 140 Sweet William, 252 Synergids, 93

t Tannins, 36f Tannosomes, 17 Tapetum, 92f, 93 Tassel, 96

325

326

Index

Tea, 224, 226 Tempering, 228, 229f Tepals, 78 Terpenoid biosynthesis, 276, 277f, 278 Terpenoids, 32f, 39–41, 41f, 261 Theca, 93 Theobromine, 213, 227 Theophylline, 228 Thylakoids, 199 Tissue culture, 44, 255 Tonoplast, 14 Tonoplast intrinsic proteins (TIP), 19 Top note, 292f, 294 Torpedo, 126f Torus, 66 Total, 294 Toxic compound extrusion‐type transporter (anthoMATEs), 168, 169f Tracheids, 63 Transcriptional regulation, 203 Transgenic, 230, 231f, 234f, 247, 248f, 274f Transgenic tomatoes, 206f Translocators, 14 Transmembrane proteins, 19 Transmitting tissue, 120, 121f, 122f Trichome, 267f, 269f Tricolpate, 2

Trinitario, 227 Tropane alkaloids, 216 Tube cell, 94

v Vanillin, 278 Vanillin biosynthesis, 279 Vegetative cell, 94 Vesicular transport, 168 Vessels, 63 Vinblastine, 216, 217f, 228 Vincristine, 216, 228 Violaxanthins, 192f Volatile terpenoids, 267f

w Wet method, 223

x Xanthophyll, 36f Xanthophylls, 192f, 197 Xylarly fibers, 57 Xylem, 61–62, 64f Xylem sap, 66

z Zeaxanthin, 192f, 197 ZING, 223

(c)

(b) (a)

Oleosomes

Plasmodesmata

Peroxisome Golgi body Nuclear membrane

Storage vacoule Crystals

Ribosomes Nucleolus

Palisade cell of leaf

Smooth endoplasmic reticulum Rough endoplasmic reticulum

Tannosome

(d)

Seed cell

(e)

Cell wall

Chromatin

Chloroplast

Plasma membrane

Anthocyanoplasts Mitochondrion

Lytic vacoules

Eudicot petal cell

Monocot floral cell

Figure 1.6  (a‐e) Plant cells show differences depending upon their role: (a) A typical plant cell, (b) Cells of mesophyll of leaves contain abundant chloroplasts due to their role in photosynthesis, (c) Seed cells of many plants store lipid in form of oil bodies or oleosomes, (d) Cells of petals of many eudicots contain large vacuoles for storing water soluble pigments in order to attract their pollinators, (e) Vacuoles of sepals and petals (perianth) of most monocots are not as conspicuous as in eudicots, as many of them are pollinated by wind.

Flowering Plants: Structure and Industrial Products, First Edition. Aisha Saleem Khan. © 2017 John Wiley & Sons Ltd. Published 2017 by John Wiley & Sons Ltd.

Plasma membrane channels

+

H

Antiporters

+

Transporters

+

H

H



+

Anions –

Channels

Plasma membrane symporters

H AA

+

H

Cd

Anthocyanin GSX pump

+

H AA

+

H +

Anions Cations

+

K H Suc

Suc

H

H

+

+

H

+

pumps

Plasma membrane pumps

Antiporters Glu Fru Suc

pumps

+

+

H

+

+

Mg

Cd +

H H H

+

H

Mg

H

pumps

Sucrose efflux carrier

Figure 1.11  An overview of intracellular communication within a plant cell which is achieved through porins present on plasma membrane as well as on other organelles. Many channels, gates and pumps present within membranes of a plant cell allow transport of molecules from one organelles to other. Note some transporters within membranes allow only one molecule to pass through them, they are uniporters, whereas some allow two molecules to pass through them within same direction, they are symporters. However, some are antiporters which allow counter‐exchange of molecules. NO3/H+, PO43‐/H+, Suc/H+ are symporters on plasma membrane, whereas Na+/H+ is an antiporter. Glu/H+, Suc/ H+, Ca2+/H+, Cd/H+, Na+/H+ and Mg+/H+ are antiporters in vacuoles. Pumps like H+, K+, Ca2+ and Cl‐ are present on plasma membrane.

(a)

(b)

(d)

(c)

(e)

Figure 2.5  (a-e) Flavonoids accumulation in flowers of eudicots serves to attract many pollinators which are not color‐blind: (a & b) Daisies and Petunia spp. accumulate different flavonoids in their petals, (c) Viola tricolor shows great variety of pigments due to hydroxyl, metoxyl, and glycosyl substituents and yellow color is due to violaxanthin, (d) Linaria maroccana, (e) Daisy flower showing different shades which are anthocyanins which give pink color (due to cyanidin‐3‐ glucoside) in ray florets and blue color (delphinidin‐3‐glucoside) in disc florets.

Transverse section Epidermal parenchyma cell Parenchyma (Ground tissue)

Cortical parenchyma cell

Epidermal Cortical cell cell

Cambial cell

Pith cell

Longitudinal & Radial section

Cambial cell

Xylem vessel

Vascular tissue (Conducting tissue) Xylem Tracheids

Scalariform

Tracheids Sieve element

Xylem

Phloem

Xylem vessel

em

em

Pith parenchyma cell

Phlo

Xyl

Cambium

Pith

Epidermis

Cortex

Figure 3.2  Stem anatomy of eudicot showing transverse, radial and longitudinal section. Note different arrangement of xylem vessels.

(c)

(a) Bordered pits

(d)

Pit aperture (e)

Water enters plasma membrane through aquaporins in most plants

Pit aperture

Pit border

(b)

In transverse view water transfer from xylem to parenchyma cells (Arrow show direction of movement) Xylem parenchyma

Pits on front side Pits on back side (dotted)

Perforation plate Xylem vessels arranged axially through perforation

Figure 3.8  (a‐e) Pits in xylem cells are involved in lateral transfer of water to neighbouring cells (in longitudinal section): (a) Bordered pits (face view), (b) Half bordered pits are present between xylem and parenchyma cells (sectional view), (c) Simple pits (face view), (d) Xylem vessels and parenchyma cells (longitudinal view), (e) Water enters plasma membrane through aquaporins in some cells.

Paradermal

Trichomes

Hexagonal cells are base cells of epidermis which form conical epidermal cells

(b)

(a)

Epidermal cells in paradermal view Trichomes

T.S of petal Xylem Phloem Collateral vascular bundle (V.B) showing xylem (in blue) and phloem (in green)

Mesophyll Collateral vascular bundle T.S

Lower epidermis Mesophyll made up of parenchyma cells

L.S of

petal

Epidermal cells Xylem

Anther (d)

Filament

Epidermal cells V.B

(c) Phloem

Bifid Stigma Style

(e)

T.S of anther lobes

Collateral vascular bundle T.S of filament

Axile placentation L.S of filament (f) Carpel

Figure 4.4  (a‐f) Floral anatomy of Petunia sp. (a) Paradermal view and T.S. of sepal, (b) Petal in three‐dimensional view showing arrangement of cells in paradermal, transverse and longitudinal section. Note the shape and position of epidermal cells, trichomes and vascular bundles (in b and c) which are mostly collateral in sepals and petals, (d) Transverse‐section of anther lobe, (e) T.S. and L.S. of filament, (f ) Carpel showing axile placentation in L.S.

(b) Growing fruit Calyx Flower bud

(c) Epidermal cells

Mesophyll

(a)

Glandular trichomes

Trichomes (d)

(e)

Mesophyll with intercellular spaces

Epidermal cells Leaflets

(f)

Anther Filament

Thorns

(g) Stigma Style

Figure 4.12  (a‐g) Floral anatomy of Rosa sp. (a) Flower, (b & c) T.S. and paradermal view of sepal, (d & e) T.S. & paradermal view of petal, (f) Anthers, (g) Stigma.

(a)

(c)

(e)

(b)

(d)

(f)

Figure 5.5  (a‐m) Life cycle of Rosa spp. (a) Bud initiation is start of gametophytic phase, (b‐c) Gametophytes of rose is monoecious and is composed of carpel in the center surrounded by cluster of stamens, (d) glandular trichomes are responsible for secretion of volatile compounds and serve to attract pollinators and also prevent flowers against microbial attack, (e‐f ) Close view of anthers (yellow) and stigma (red), (g‐i) pollens in Rosa spp., (j‐l) stages in fruit and seed formation. Young fruit (rose hips) are green and their ripening is indicated by carotenoids accumulation in epidermal cells of exocarp, (m) seed formation.

(g)

(i)

(h)

(j)

(k)

(l)

(m)

Figure 5.5 (Cont’d)

Papillar cell on stigma

(a)

Dorsal V.B Epidermis Cortex

(b)

Citric acid cycle & ATP synthase provide energy for pollen growth

Pollen germination CAC

Solid style supporting pollen tube growth through transmitting tissue

Ventral V.B showing xylem (in red) and phloem (in blue) Callose plugs in growing pollen tube

Golgi body Mitochondria

Transmitting tissue Sperm cells

Epidermis

ER vesicles

Ovary with ovules

Tube nucleus Style transmitting tissue Secondary wall Pollen tip with Golgi vesicles

Funiculus Septum

Figure 5.11  (a‐b) (a) Development of pollen tube through style, (b) Main events on the pollen tip.

(a)

(b)

(c) Septum

Dorsal V.B

Septum

Orthotropous ovules

Pollen tube

Carpel

Locule

(e)

Ventral V.B showing xylem (in red) and phloem (in blue) (d) Chalazal end

Ovary wall

Antipodal cells Outer integument

Sperm nucleus Zygote formation

Sperm nucleus tube Pollen tip

Synergids

Micropyle Sperm cells enter micropyle Pollen tube within ovule

Funiculus Inner integument

Polar nuclei of central cell Vacuole

Egg cell

Figure 5.12  (a-e) A summary of events of sexual reproduction in angiosperms starting from pollination to fertilization, (a &b) T.S. of carpel showing trilocular ovary, (c) Trilocular ovary showing unfertilized ovules, (d) A close view of female gametophyte showing entry of pollen tube, (e) Entry of pollen tube and main events in fertilization.

(a)

(b)

(c)

Ovary wall

Developing fruit wall

Locule

Embryo proper Suspensor Basal cell

Cotyledons Globular shape embryo Heart shape embryo (e)

Hypocotyl

Torpedo

(d) Vascular bundles (phloem-blue, xylem-red)

Epidermis

Mesocarp Mature fruit wall (Exocarp) Fertilized ovule (seeds) (Endocarp)

Seed coat Cotyledons (Dicot) Endosperm Ground tissues Suspensor Mature embryo (seed)

Mature ovules (seed) within developing fruit

Figure 5.13  (a-e) Post‐fertilization stages in angiosperms starting from embryo formation to fruit formation: (a) Globular‐shaped embryo, (b) Heart‐shaped embryo, (c) Torpedo‐stage, (d) T.S. of developing fruit showing fertilized ovules (seeds), (e) Mature embryo (dicot seed).

(a)

(b)

Mid-vein

(c) Epidermis Palisade mesophyll cells

(d)

Xylem

Main-vein surrounded by anthocyanic parenchyma cells

Phloem

(f)

(e) Vascular veins

(g) Epidermis Palisade anthocyanic cells Mid-vein

Anthocyanins accumulated in adaxial epidermal cell Xylem Phloem

Figure 7.1  (a-g) Genes encoding anthocyanins are expressed during different stages of a plant either in response to some stress or as a genetically controlled characteristic of plants. In many plants like, Psidium guajava, anthocyanin accumulation takes place in different areas within leaves. (a‐c) Anthocyanins accumulation in cells surrounding mid‐vein and vascular tissues, (d) Upon maturity, leaves become green, (e‐g) During senescence, genes encoding anthocyanins are expresses in lamina of leaf except vascular tissues.

(b)

(a)

Serrate margins

Mid-vein

(c) (d) Anthocyanin accumulation in adaxial (upper) epidermal cells

(f) Mid-vein

Serrate margins

Epidermis

(e)

Xylem Phloem Trichomes Anthocyanic vacuole of epidermal cell

Figure 7.2  (a-f) Many Rosa spp. accumulate anthocyanins during different stages. In roses anthocyanins exist as anthocyanidin mixtures. Their expression in petals of rose flower is a genetically controlled feature. However, expression of anthocyanins in leaves, petioles, and ligules of Rosa spp. species seems to be in response to certain abiotic and environmental factors, (a & b) In young juvenile leaves, their role seems to protect photosynthetic apparatus from high intensities of light or against temperature and give whole lamina red color, (c & d) Serrate margins of rose leaves accumulate anthocyanins in their adaxial epidermal cells (paradermal section), (e) Genes for anthocyanins are also expressed in glandular trichomes of leaves, (f ) Three‐dimensional view of rose leaf showing anthocyanin accumulation in adaxial epidermal cells of leaves.

(a) (b) Petiole

Xylem (d)

(c)

Anthocyanin accumulation in epidermis

i ng

ew

vi

di

tu

(e)

l na

Phloem

Lo

Anthocyanic vacuole

Epidermal cells Phloem

Xylem

Cortical region

Figure 7.9  (a-e) Genes for anthocyanins are also expressed in petioles and pedicels which might be an indication of their sensitivity against UV‐radiation: (a) Petiole of Euphorbia pulcherrima appears pink in color due to accumulation of anthocyanins. Note the appearance of pink color in petiole, where genes for anthocyanins are expressed, (b & c) T.S. of petiole showing anthocyanin accumulation in epidermal and sub‐epidermal cells, (d) longitudinal section of epidermal cells of petiole showing anthocyanin accumulation, (e) Three‐dimensional view of petiole of E. pulcherrima.

Applications of carotenoids in industries

Agriculture & plant breeding programs

Food products

Food color

Carrot

Feed additives for poultry

Tomato

Dietary carotenoids

Nutraceutical & pharmaceutical

Eye health

Cardiovascular health

Ornamental hybrids containing carotenoid pigments

Marigold

Development of tobacco resistant plant through altering carotenoid biosynthesis pathways

Floriculture

Development of transgenic tomatoes to increase their nutritional value by altering β-genes (beta genes in tomatoes)

Overproduction of β-carotenes to meet vitamin A deficiency in potatoes, corn & flax through regulation of fruit specific regulators

Ronen et al. 2000 (used with permission from National Academy of Science, U.S.A)

Figure 8.11  Major applications of carotenoids in industries.

Transcriptional regulation of carotenoids in fruits to enhance their color & increase their demand in market

Water

Water + Beans

ScCO2+Caffeine

Caffeine

High Pressure extraction vessel

Caffeine dissolves in water in absorption vessel

Water

ScCO2 Caffeine Commercial use of caffeine Decaffeinated Beans Cosmetic products Pharmaceutical products Soda Drink (Slimming products, perfumes, creams) (Pain killers) (Mountain Dew, Sprite, Coke)

Instant coffee Cappuccino Mocha

Espresso

Figure 9.6  Steps in industrial manufacture of decaffeinated coffee through supercritical CO2 method and uses of beans in beverage products.

(a)

(b)

(c)

(d)

(e)

(f)

Figure 10.4  Transgenic cultivars of blue roses containing delphinidin. The rose cultivars WKS77, WKS82, WKS100, WKS116, WKS124 and WKS140 transformed with pSPB130 (left, host; right, a transformant). A flower of the line exhibiting the most significant color change is shown. (a) WKS77, (b) WKS82, (c) WKS100, (d) WKS116, (e) WKS124, (f ) WKS140 (Katsumoto et al., 2007). (Used with Permission from Oxford University Press.)

(a)

(b)

Figure 10.5  (a‐b) (a) Dianthus barbaratus known as sweet William is an important carnation in floriculture, (b) D. caryophyllous (sweet William) is a carnation with possible anti‐HIV potential.

Volatile signals for pollination & defense

Attracts insect or a fly for pollination

Fruit essential oils Linanool, α-Pinene, α-Terpentine, Geranyl acetate, Camphor, Geraniol, β-Pinene, Myrcene, Limonene, P-cymol, Dipentene

Repels bacteria

α-Terpentine, α-Decylaldehyde, Borneol, Acetic acid ester

Cuticle Volatiles released in cytosol

Mature leaves

Plastid

Trichomes

(b) Leaf showing glandular trichomes

(a) Coriandrum sativum

(c) Trichome showing monoterpene formation in plastid

Cold water

Still

Steam

Cooling coil Sieve

Essential Volatiles

Hot water

Essential oils Condenser Water Water & essential oil Fire Floral water

Linalool containing cosmetic products

Face cream

Figure 11.5  (a-d) Linalool, a monoterpenoid, acts as a defensive compound and a volatile attractant. It is known to be synthesized by over 200 plants. Many members of family Apiaceae synthesize linalool as a part of their defense to keep their predators away. (a) Coriandrum sativum plant, (b) In C. sativum, linalool synthesis takes place within plastids of glandular trichomes located on epidermal cell from where it diffuses in air, (c) DMAPP and IPP serve as precursors for synthesis of essential oil of C. sativum which is a mixture of many volatile monoterpenoids, including linalool, geraniol, and many other volatile molecules (shown in (a)), (d) Extraction of essential oils like linalool from linalool‐synthesizing plants like C. sativum is done through steam distillation method which is a temperature sensitive method used commonly for extraction of essential oils and results in the separation of volatile molecule from plant tissues. Volatile molecules are passed through condenser in which vapors are condensed and essential oils are then collected in another vessel along with floral water, (c) Linalool is commonly used essential oil in many cosmetic and pharmaceutical products.

(g) (f)

(h) Condenser (gaseous)

(e)

(d)

CO2 storage tank (liquid)

(Liquid gaseous)CO2

(Separator extract)

(Extractor E2)

(Extractor E1)

Floral extract

(a)

CO2 Heater (31°C) (Supercritical)

(Liquid) Pressure controlling pump >74

(Condenser liquid)

(c)

(b)

Figure 12.6  (a‐e) Supercritical CO2 method is one of the reliable and efficient method used for making perfumes: (a) CO2 (liquid) is passed through condenser, (b) Pressure of flow is maintained by pump, (c) CO2 heater converts CO2 in supercritical form, (d‐e) CO2 in its supercritical form enters extraction vessels (E1 and E2), (f ) It is followed by separation of volatiles from liquid CO2 in a separation vessel, (g) CO2 recovery as gaseous state in a condenser, (h) storage in a tank.

Plasmid with genes (c) encoding MVA pathway

(b)

MVA pathway

MVA pathway

(a) Cell of petal of Rosa sp.

Geraniol Limonene Linalool Citronellol

(d) E coli.

Aromatic gene inserted in E coli.

(e) Bioengineered perfume

Figure 12.10  (a‐e) Steps in making of genetically engineered aromatic bacteria: (a) Cell of petal of Rosa sp., (b) Genes for MVA pathway which forms volatile molecules from plants like roses are incorporated in plasmids, (c) Transformed plasmids are incorporated in bacteria like E. coli, (d) Transgenic E. coli with MVA pathway, (e) Aromatic bacteria are used in making perfumes, cosmetics and pesticides in order to minimize use of plants for making perfumes and cosmetic products.