Phytomedicines, herbal drugs, and poisons PDF
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PHYTOMEDICINES, HERBAL DRUGS, AND POISONS PHYTOMEDICINES, HERBAL DRUGS, AND POISONS Ben-Erik van Wyk Michael Wink The University of Chicago Press Chicago and London Conceptualized and developed by Briza Publications, South Africa www.briza.co.za Copyright © 2014 in text: Ben-Erik van Wyk and Michael Wink Copyright © 2014 in photographs: Ben-Erik van Wyk and individual photographers listed Copyright © 2014 in published edition: Briza Publications All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means without written permission of the copyright holders. IMPORTANT WARNING This book is a scientific review of medicinal and poisonous plants and not a medical handbook. Some of the plants described may result in death, serious intoxication, severe allergies and other harmful effects. None of the statements in this book can be interpreted as a recommendation to experiment with any of the plants. Neither the authors nor the publishers can be held responsible for claims arising from the mis- taken identity of plants or their inappropriate use. Do not attempt self-diagnosis or self-treatment. Always consult a medical professional or qualified practitioner. Joint publication with the Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK. www.kew.org and The University of Chicago Press, Chicago 60637 The University of Chicago Press, Ltd., London 23 22 21 20 19 18 17 16 15 1 2 3 4 5 ISBN-13: 978-0-226-20491-8 (cloth) ISBN-13: 978-0-226-20507-6 (e-book) Royal Botanic Gardens, Kew ISBN-13: 978 1 84246 515 8 (cloth) The views expressed in this work are those of the individual authors and do not necessarily reflect those of the publisher or of the Board of Trustees of the Royal Botanic Gardens, Kew. Library of Congress Cataloging-in-Publication Data Van Wyk, Ben-Erik, author. Phytomedicines, herbal drugs, and poisons / Ben-Erik Van Wyk and Michael Wink. pages cm Includes index. ISBN 978-0-226-20491-8 (cloth : alk. paper) — ISBN 978-0-226-20507-6 (e-book) 1. Herbs—Therapeutic use. 2. Medicinal plants. 3. Botany, Medical. I. Wink, Michael, author. II. Title. RM666.H33V367 2015 615.3’21—dc23 2014046645 ∞ This paper meets the requirements of ANSI/NISO Z39.48-1992 (Permanence of Paper). DOI: 10.7208/chicago/9780226205076.001.0001 Project manager: Reneé Ferreira Cover design: Lauren Smith Inside design and typesetting: Alicia Arntzen, The Purple Turtle Publishing CC Reproduction: Resolution Colour, Cape Town E-book conversion: Trace Digital Services, Cape Town Contents Preface 6 Introduction 7 Traditional systems of medicine 8 Phytomedicines 16 Functional foods and nutraceuticals 18 Plant-derived chemical compounds 20 Mind altering drugs and stimulants 22 Plant poisons 24 - Plant parts used 28 Dosage forms 30 Methods and routes of administration 34 Extraction and analysis of compounds 36 Quality control and safety 40 Efficacy of herbal medicine 42 Pharmacological and toxic effects 44 Regulation and legal aspects 46 Overview of secondary metabolites 48 Photographic index of plants 92 Glossary 274 Further reading 285 Acknowledgements and photo credits 288 Index 289 Preface Aide-mémoire to the Medicinal Plant Sciences or Natural Products in a Nutshell could have been equally ap- propriate titles for this bird’s eye view of medicinal and poisonous plants. The aim is to present the reader with a compact, fully illustrated, multilingual and user-friendly reference guide. The book covers 360 species of commercially relevant and well-known medicinal plants, including those used for their poisonous or mind-altering activities. It also briefly explains the basic concepts related to the botany, chemistry, pharmacology and use of these plants. There are few books that cover the entire spectrum of medicinal, poisonous and mind-altering plants, a wide and complicated field of study. Not only are there thousands of plant species that are used in one way or an- other, but also many different medicinal systems and cultural groups that each have their own materia medica and their own ways of using plants. This makes for a fascinating and never-ending scientific exploration, to discover and to learn. At the request of readers and publishers, we have attempted to condense a large volume of data and concepts into a limited number of pages, in order to present an affordable yet colourful summary of the most impor- tant facts relating to medicinal and poisonous plants from all corners of the earth. This book should be viewed as a convenient and user-friendly starting point (a desk-top reference guide) to get quick, scientifically accurate answers to basic questions. Those who want to delve deeper into the subject can refer to our two other, more comprehensive reviews: Medicinal Plants of the World and Mind-altering and Poisonous Plants of the World, as well as the many scientific references that are cited there. In our fast-moving modern world, knowledge has become freely available on an unprecedented scale. There are excellent books on almost any conceivable aspect of medicinal botany and hundreds of thousands of scientific papers describ- ing the details of chemical studies and pharmacological evaluations of plant compounds and extracts. Added to this is the worldwide web, where huge amounts of data can be accessed instantaneously. These sources generally provide the long answers, not the short ones. Our target audience covers the full range of readers: interested lay people who may want to use the book as an illustrated encyclopaedia, students of botany and pharmacology who need to prepare for an examination, professional persons working in the commercial environment and even academics and researchers who want to save time and need a quick reference guide and mnemonic aid. Ben-Erik van Wyk and Michael Wink 1 September 2014 6 Introduction This book is intended to be a handy desktop reference book to well-known medicinal and poisonous plants of the world. It is aimed at providing health care professionals, pharmacists, doctors, students and all other interested persons with quick answers to basic questions about medicinal and poisonous plants. Fundamental concepts, terms and methods relevant to the subject are briefly defined and discussed in short introductory chapters. The aim is to provide scientifically rigorous and accurate information in a study field that is rapidly changing and adapting to the modern way of life. The use of medicinal, mind-altering and poisonous plants is often associated with folk medicine, practised in distant rural areas where access to modern health care is not available. However, the popularity of natural remedies and botanicals in the modern world cannot be denied, as is seen in the rapid growth of over-the- counter medicines, dietary supplements and functional foods. Many people are taking control of their health by eating a balanced diet, getting regular exercise and using natural medicines and supplements that may help with the prevention and cure of ailments and imbalances. It therefore seems likely that basic knowledge about plant products and their chemical constituents will become increasingly important in the future, as we strive towards better health and a longer, happier life. There are still many questions about the safety and efficacy of plant-derived products. Some of the answers can be found in this book. It is, however, likely that modern science will not only make dramatic new discov- eries in health care, but also provide a deeper understanding of age-old principles that seemed implausible from a reductionist perspective. It took science more than 200 years to discover why limes (lemons) can pre- vent scurvy; it is not unreasonable to expect that profound new insights still lie ahead in the distant future, despite our best efforts to apply modern technology and the principles of science. When it comes to biology and human health, we know what we do not yet know (and therefore try to find answers to our questions through scientific research) but we also do not know what we do not yet know (and therefore eagerly await ground-breaking discoveries that will allow us to ask the right questions). Mallow (Malva sylvestris): source of anthocyanin pigments 7 Traditional systems of medicine The majority of people on earth still rely on traditional medicine for their primary health care needs. Mod- ern allopathic medicine not only co-exists in parallel to the systems from which it was derived, but is often enriched by new discoveries based on ancient knowledge and experience. In general, traditional herbal rem- edies are used to alleviate the symptoms of chronic and self-terminating illnesses, while allopathic medicines are called upon in case of serious and acute health conditions. Ancient origins benefits than for their nutritional value; others are used not to cure any ailments but to prevent them There is evidence that primates such as chimpan- in the first place. It is very likely that all medi- zees and gorillas sometimes ingest particular plants cines were originally eaten or chewed, as can still not as food but for their medicinal value. The use be seen in hunter-gatherer communities. Dosage of plants as medicine may therefore have a very forms such as infusions, decoctions and tinctures long history. Recent evidence from southern Africa must have been a much later development. Some shows that human abstract thinking dates back to plants were used for ritual and religious purposes, at least 140 000 years ago. This means that most of especially those with hallucinogenic properties the history of how medicines developed was never that provided insights into other realms and other recorded. It is likely that a lengthy process of trial worlds. Ancient systems also incorporate mental and error resulted in some remedies being rejected health, harmony and balance as important under- as ineffective and perhaps dangerous, while others lying principles of a good life. became important cures. The results of these ex- periments were no doubt passed on verbally from African medicine one generation to the next. In the absence of writ- ten records and to ensure maximum mnemonic African Traditional Medicine probably dates value, important elements of the cure (i.e., the di- back to the origins of our species and represents agnosis of the ailment, the identity of the plant and the most diverse but also the least systematised and the methods of administration) may have been in- most poorly documented of all medicinal systems. tricately linked to one another within mythological There are many regional differences, reflecting the stories, songs or poems. It is also likely that super- extreme biological and cultural diversity of sub- stition and magic played important roles as ways Saharan Africa, including local plant endemism in which people without scientific insights tried to and local cultural customs. Common to all is ho- make sense of what they observed. For example, lism, in which both body and mind are treated: disease is often associated with evil spirits, which the underlying psychological basis of the illness is is quite understandable if you have no access to a first attended to, after which herbs and other medi- microscope. The act of “chasing away evil spirits” cines are prescribed to alleviate the symptoms. The is almost certainly equivalent to our modern-day ancient practices of the click-speaking people of practice of using disinfectants and antiseptics. southern Africa are particularly interesting, not Traditional medicine is also dynamic and adap- only because they represent the most ancient of tive, as can be seen by the rapid incorporation of human cultures, but also because their traditional recently introduced plant species into the materia home is an area of exceptional plant endemism. In medica. The process of trial and error was some- South Africa, an integration of Khoi-San and Cape times guided by the “doctrine of signatures”, based Dutch healing methods has resulted in a distinct on the belief that the Creator has provided the and unique healing system, for which the name plants themselves with clues as to how they should Cape Herbal Medicine was recently proposed. be used. Milky latex, for example, may indicate The remarkably diverse materia medica typically therapeutic value in promoting lactation; red sap includes general tonics, fever remedies, sedatives, is associated with blood and may suggest efficacy stomachics, diuretics, laxatives and many wound- in treating menstrual ailments; yellow sap suggests healing plants. Tropical Africa and especially West value as cholagogue, to increase or decrease bile and East Africa represent a rich diversity of medici- flow, and so on. In traditional cultures there is not nal plants and human cultures. Examples of locally such a sharp distinction between food and medi- important medicinal plants in Ethiopia include cine. Some products are eaten more for their health Echinops kebericho, Embelia schimperi, Glinus 8 San healing dance San rock art showing aloes Ancient rock engraving showing bushman poison bulb Juice resembling blood (Pelargonium antidysentericum) (Boophone disticha) Coffee (Coffea arabica) – the most popular of all stimulant Khat (Catha edulis) –wrapped in banana leaves to keep fresh beverages lotoides, Hagenia abyssinica, Lepidium sativum, biscus sabdariffa (hibiscus or roselle), Hypoxis Moringa stenopetala, Phytolacca dodecandra, Ruta hemerocallidea (African potato), Ricinus commu- chalepensis and Taverniera abyssinica. The com- nis (castor oil plant) and Prunus africana (African mercially most relevant African medicinal plants cherry or red stinkwood). There are many hunt- have been described in a recent African Herbal ing poisons [e.g. Adenium obesum (desert rose), Pharmacopoeia. It includes Acacia senegal (gum Boophone disticha (bushman poison bulb)], ordeal arabic), Agathosma betulina (buchu), Aloe ferox poisons [e.g. Physostigma venenosum (calabar (Cape aloe), Artemisia afra (African wormwood), bean), Erythrophleum suaveolens (ordeal tree)] Aspalathus linearis (rooibos tea), Boswellia sacra and stimulants [e.g. Catha edulis (khat), Coffea (frankincense), Commiphora myrrha (myrrh), arabica (coffee) and Sceletium tortuosum (kanna Harpagophytum procumbens (devil’s claw), Hi- or kougoed)]. 9
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