Plant Secondary

Metabolism

ine of Plant Secondary Metabolism

C6C1-compounds

t shikimic acid

I chorismic acid

cyclitols, polyols

glycosides

chlorophyll + C 0 2 + light

photosynthesis

carbohydrates

glycolysis

£so-chorismic acid

coumarins Iigni n lignans

pentose phosphate

erythrose 4-phosphate

phosphoenol pyruvate

cyanogenic glycosides * glucosinolates

peptides • proteins

non-protein amino acids

f tricarboxyli c acid

amino acids cycle acids

alkaloids t e r ^ n ° i d

alkaloids

s-ternenes ^ roev . .

^ ^ / / waxes

I acetylenes

rotenoids / hydrocarbons polyketides

• phenols phenylpropanoid \ naphthoquinones

compounds \ anthraquinones condensed tannins

flavonoids

Plant Secondary

Metabolism ]David S. Seigler

Department of Plant Biology University of Illinois, Urbana

SPRINGER SCIENCE+BUSINESS MEDIA, L L C

CIP

Library of Congress Cataloging-in-Publication Data

Seigler, David S. Plant secondary metabolism / David S. Seigler.

p. em. Includes bibliographical references. ISBN 978-1-4613-7228-8 ISBN 978-1-4615-4913-0 (eBook) DOI 10.1007/978-1-4615-4913-0 1. Plants--Metabolism. 2. Metabolism, Secondary. 3. Botanical

chemistry. r. Title. QK887.538 1995 581.1'33--DC20 89-70112

Copyright © 1998 by Springer Science+ Business Media New York Originally published by Kluwer Academic Publishers in 1998 Softcm-er reprint of the hardcover 1st edition 1998

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, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher.

Printed on acid-free paper.

This printing is a digital duplication of the original edition.

Table of Contents

Preface vii Chapter 21 Sesquiterpenes 367 Acknowledgments ix Chapter 22 Diterpenes and Sesterterpenes 398 Chapter 1 Introduction 1 Chapter 23 Triterpenes and Steroids 427 Chapter 2 Fatty Acids 16 Chapter 24 Saponins and Cardenolides 456 Chapter 3 Acetylenic Compounds 42 Chapter 25 Limonoids, Quassinoid., and Related Chapter 4 Plant Waxes 51 Compound. 473 Chapter 5 Polyketides 56 Chapter 26 Tetraterpenes or Carotenoids 486 Chapter 6 Benzoquinones, Naphthquinones, and Chapter 27 Introduction to Alkaloids 506

Anthraquinones 76 Chapter 28 Simple Amines, Simple Aromatic and Chapter 7 Shikimic Acid Pathway 94 Pyridine Alkaloids 513 Chapter 8 Phenylpropanoids 106 Chapter 29 Pyrrolidine, Tropane, Piperidine, and Chapter 9 Coumarins 130 Polyketide Alkaloids 531 Chapter 10 2-Pyrones, Stilbenes, Chapter 30 Pyrrolizidine, Quinolizidine, and

Dihydrophenanthrenes, and Xanthones 139 Indolizidine Alkaloids 546 Chapter 11 F1avonoids 151 Chapter 31 Alkaloids Derived from Anthranilic Chapter 12 Tanuins 193 Acid 568 Chapter 13 Nonprotein Amino Acids 215 Chapter 32 Isoquinoline and Benzylisoquinoline Chapter 14 Peptide. 234 Alkaloids 578 Chapter 15 Carbohydrate. 247 Chapter 33 Alkaloids Derived from Both Tyrosine Chapter 16 Cyanogenic Glycosides and and Phenylalanine 617

Cyanolipids 273 Chapter 34 Indole Alkaloids 628 Chapter 17 Glucosinolates 300 Chapter 35 Ergot and Other Indole Alkaloids 655 Chapter 18 Introduction to Terpenes 312 Chapter 36 Alkaloids of Terpenoid Origin 668 Chapter 19 Monoterpenes 324 Chapter 37 Miscellaneous Types of Alkaloids 692 Chapter 20 Iridoid Monoterpenes 353 Index 713

Preface

Life has evolved as a unified system; no organism exists alone, but each is in intimate contact with other organisms and its environment. Historically, it was easier for workers in various disciplines to delimit artificially their respective areas of research, rather than attempt to understand the entire system of living organisms. This was a pragmatic and neces­sary way to develop an understanding for the various parts. We are now at a point, however, where we need to investi­gate those things common to the parts and, specifically, those things that unify the parts. The fundamental aspects of many of these interactions are chemical in nature. Plants constitute an essential part of all life systems; phytochemistry provides a medium for linking several fields of study.

It is partially through teaching a course in phytochemistry that I have come to realize more fully the potential of phyto­chemical studies to unite and integrate a vast amount of material from different disciplines. The diversity of students that have taken this course and their research interests also reflects the utility and value of this type of information. Among the fields represented are Biology (Ecology, Ento­mology, Plant Biology, Botany, Physiology, Microbiology, and Zoology), Geology (Organic Geochemistry), Chemistry (Organic Chemistry, Biochemistry, and Analytical Chemis­try), Agriculture (Horticulture, Animal Science, Dairy Sci­ence, Forestry, Agronomy, and Plant Pathology), Veterinary Medicine, and Food Science. Possibly because of the diffi­culties involved in integrating such a diversity of interests, no adequate text presently exists for this course.

In this text, I propose to survey our present knowledge of the phytochemistry and the role that secondary metabo­lites play in biological relationships. These relationships bas­ically fall into two categories: the first concerns the function and value of the compounds within the plants themselves. Many compounds are catabolized for energy or used to fulfill other requirements that involve nitrogen. For example, fatty acids from triglycerides have long been recognized as energy sources for the embryo of a germinating seed. Recently, a

similar role also has been suggested for fatty acids from cyanolipids. Nonprotein amino acids, cyanogenic glyco­sides, and the non-fatty-acid portion of cyanolipids also are incorporated into primary metabolites during germination. Secondary metabolites of these structural types are accumu­lated in large quantities in the seeds of several plant groups where they probably fulfill an additional function as deter­rents to general predation.

The second type of relationship involves interaction of plants with other organisms and with their environment. Bio­logical interactions must be viewed in the light of evolution­ary change and the coadaptation, or perhaps coevolution, of organisms. A plant that possesses the ability to synthesize a compound that disturbs the physiological functions of a herbivore may have a selective advantage over one that does not. The chemical abilities of the plant may be utilized to establish interlocking relationships within the contexts of pollination, seed dispersal, establishment of mycorrhizal fungi, or protection of the plant by another organism, such as ants. The "advantage" gained from such interactions may be offset by metabolic cost or self-toxicity, but the process of natural selection optimizes these interacting factors. Thus, assuming the system remains stable for a sufficient time, eqnilibrium will be reached. Finally, it must be remembered that all organisms in a given system are evolving. Interacting organisms have the ability to adapt to changes in plant chem­istry and morphology, and may eventually ntilize plant hosts that were formerly unacceptable. Host selection, food prefer­ences, taste, toxicity, wounding responses, allelopathy, and a vast array of other topics are the results of these evolutionary processes.

An understanding of the biosynthetic pathways leading to secondary metabolites and a recognition of the chemical structural types present and their distribution among plant groups have proven useful for the study of biosystematic problems and for achieving an understanding of plant phylo-

vii

viii Preface

geny. The predictive value of chemotaxonomic information has been recognized by natural products chemists.

Plant secondary compounds play an important role in in­dustry and medicine. Many industries are based on flavoring agents and perfumes, rubber, and naval stores. Several sec­ondary compounds are physiologically active, which results in their use as insecticides, medicinal agents, or biological probes or "tools." Plant compounds that are toxic to man and domestic livestock are widespread and may be responsi­ble not only for accidental but also for chronic poisoning by common foods such as cassava, sago, lima, and fava beans.

Subjects are grouped on the basis of major chemical struc­tural types. Each will be discussed in terms of biosynthesis and distribution, diversity of known structures, taxonomic application, biological function, toxicity, and medicinal and industrial uses. I do not present an encyclopedic coverage of all available literature. Rather, the goal is a readable, inte­grated text that will be suitable for instruction at the ad­vanced undergraduate as well as the graduate level. In gen­eral, only phytochemical (Le., plant chemical) data has been included, although information about the chemistry of in-

sects, marine organisms, bacteria, fungi, and other organisms has been incorporated where warranted.

No attempt has been made to reference exhaustively all information cited in the text. Many references given are to review articles and in many instances are not those of the workers who carried out the original work. Although an at­tempt has been made to give the structures of most com­pounds given in the text, some are not included. Further, the structures of some representative compounds are included in figures, but, as they are not specifically cited in the text, they are not given numbers.

I apologize to authors inadvertently misquoted and will attempt to correct errors in any future editions. As it is diffi­cult to locate many references dealing with topics discussed in this text, I solicit comments and any pertinent information that may be useful for correction of errors or for the prepara­tion of further editions and wish to thank those who have already provided me with manuscripts, reprints, unpublished material, suggestions, and assistance in preparing this pres­ent manuscript. ffitimately, of course, I stand responsible for the conclusions and statements made in this text.

Acknowledgments

I wish to thank Anita Brinker, H. David Clarke, Ute Ecken­bach, Richard Lindroth, Karin Readel, and Kurt Potgieter for reading earlier versions of portions or the entire manu­script and making suggestions for improvement. The techni­cal assistance of Susan Gibbons, Elizabeth Bartlett, Cheryl Frankfater, Nathaniel Ohler, and Ulrike Nolte also is greatly appreciated. The comments of J. Balsevich, K. Brown, S. A. Brown, E. E. Conn, K. R. Downum, G. Cordell, D. Gian­nasi, J. Gershenzon, J. B. Harbome, E. Leistner, S. Mole, A. Nahrstedt, R. G. Powell, P. Reichard, G. A. Rosenthal, T. J. Simpson, K. Schreiber, P. Waterman, and anonymous reviewers have been extremely useful in revising the manu­script. Greg Payne of Chapman & Hall has provided many helpful suggestions.

In a number of cases, topics were reviewed in term p'apers submitted by students of the Plant Secondary Metabolites or the Chemical Ecology course. Information from these papers was extremely helpful and I especially wish to thank the following stndents: John Andersen, Du-Jong Baek,

David C. Breeden, Anita Brinker, Stacie E. Canaan, H. David Clarke, Paul R. Connelly, Katherine Dowd, Thomas Dudman, Nicole Duffee, Candace Easter, Robert J. Eilers, John Gerlits, Peter Gottschalk, Mark Hediger, Ellen Hei­ninger, Tricia HooChung, Han-Young Kang, Frederick J. Lang, Wei Jane Liao, Hengchen Lin, Vincent Ling, Randall A. Lovell, John Martini, Susan McCarthy, John Ng, James Nitao, Paul Ode, Mark S. Pavlin, Raymond Pedersen, Char­lotte Read, Karin Readel, Nelson T. Rotto, Claire Rutledge, Michael J. Sophia, Andrew L. Staley, Larry J. Thompson, Martin B. Wolk, and Craig M. vanZyl.

This work would not be possible if it were not for some of my former teachers and mentors including Allie Marie Hobbs, Donald Hamm, Jordan J. Bloomfield, Leon Cieres­zko, Eric Conn, Dale M. Smith and Tom Mabry.

I also wish to express my appreciation to my wife Janice for her patience during the preparation of this book. She bas assisted in many ways to further this work.

Ix