Until relatively recently pharmacognosy was regarded, almost exclusively, as a subject in the pharmaceutical curriculum focused on those natural products employed in the allopathic system of medicine.
Coincident with the increasing attractiveness of alternative (complementary) therapies and the tremendous range of herbal products now generally available to the public, regulatory requirements covering medicinal herbs have been put in place by many countries in order to control the quality of these products. Monographs are now available on a large number of such drugs giving descriptions, tests for identity and purity and assays of active constituents. These monographs are being compiled by a number of bodies (see below). In this respect rec- ognition should be given to the pioneering production of the British Herbal Pharmacopoeia, first produced in 1974 with the latest volume in 1996
. Pharmacognosy is also important in those countries having their own systems of medicine in which plants are important components. Many crude drugs once generally categorized as herbal remedies are now, in accordance with Continental European practice, described in the British Pharmacopoeia (BP). Chromatographic, chemical and physical tests, together with assay procedures, are given for many drugs for which previously there was no quantitative evaluation of the chemical constituents available. The importance of quality control is paramount, as the demand and the possibility of substitution has increased.
The upsurge in the marketing of Chinese and Asian tradi- tional medicines worldwide, for which there is a need for adequate control, adds a further dimension to pharmacognosy; pharmacopoe- ial monographs now include Liquorice for use in Chinese medicine, Chinese angelica root and Astragalus root. It is understood that further monographs on Chinese and Indian drugs for use in traditional medi- cine are to be included in the BP 2009. Although pharmacognosy is principally concerned with plant materials, there are a small number of animal products which are traditionally encompassed within the subject; these include such items as beeswax, gelatin, woolfat, vitamins, etc. Other natural prod- ucts such as the antibiotics, hormones and others may or may not be involved, depending on the teaching practice of a particular institution.
Marine organisms, both plant and animal, with potent pharmaco- logical actions are receiving increasing attention in the search for new drugs. Materials having no pharmacological action which are of inter- est to pharmacognosists are natural fibres, flavouring and suspending agents, colourants, disintegrants, stabilizers and filtering and support media. Other areas that have natural associations with the subject are poisonous and hallucinogenic plants, allergens, herbicides, insecti- cides and molluscicides. Vegetable drugs can be arranged for study under the following headings
. 1. Alphabetical. Either Latin or vernacular names may be used. This arrangement is employed for dictionaries, pharmacopoeias, etc. Although suitable for quick reference it gives no indication of inter- relationships between drugs.
2. Taxonomic. On the basis of an accepted system of botanical classification (Chapter 3), the drugs are arranged according to the plants from which they are obtained, in classes, orders, families, genera and species. It allows for a precise and ordered arrangement and accommodates any drug without ambiguity. As the basic botan- ical knowledge of pharmacy students decreases over the years this system is becoming less popular for teaching purposes.
3. Morphological. The drugs are divided into groups such as the follow- ing: leaves, flowers, fruits, seeds, herbs and entire organisms, woods, barks, rhizomes and roots (known as organized drugs), and dried lati- ces, extracts, gums, resins, oils, fats and waxes (unorganized drugs). These groupings have some advantages for the practical study of crude drugs; the identification of powdered drugs (see Chapter 43) is often based on micro-morphological characters.
4. Pharmacological or Therapeutic. This classification involves the grouping of drugs according to the pharmacological action of their most important constituent or their therapeutic use. R. Pratt and H. W. Youngken Jr. were, in 1956, the first to use this approach for an English language textbook and now, with so many plant materi- als being screened for specific pharmacological activity, this type of listing is found increasingly in the literature. Its use is illustrated in Chapters 27–32. However, it is important to appreciate that the constituents of any one drug may fall into different pharmacologi- cal groups.
5. Chemical or Biogenetic. The important constituents, e.g. alkaloids, glycosides, volatile oils, etc., or their biosynthetic pathways, form the basis of classification of the drugs. This is a popular approach when the teaching of pharmacognosy is phytochemically biased. Ambiguities arise when particular drugs possess a number of active principles belonging to different phytochemical groups, as illus- trated by liquorice, ginseng, valerian, etc. The scheme is employed in Chapters 19–26 for arranging the established pharmacopoeial drugs.
The following list of works, arranged in the above five groups, will serve as examples and also provide a useful list of textbooks and works of reference; those no longer in print may be found in established pharmaceutical libraries. 1. Alphabetical Barnes J, Anderson LA, Phillipson JD 2007 Herbal medicines, 3rd edn. Pharmaceutical Press, London Bisset NG (ed), Wichtl M 1996 Herbal drugs, a handbook for practice on a scientific basis. Medpharm Scientific Publishers, Stuttgart Bradley PR 1992, 2006 British herbal compendium, Vols I, II. British Herbal Medicine Association, Bournemouth, UK British Pharmacopoeia 2008 and preceding edns British Herbal Pharmacopoeia 1996. British Herbal Medicine Association, Exeter, UK Duke JA 2002 Handbook of medicinal herbs, 2nd edn. CRC Press, New York Martindale: the Complete Drug Reference, 35th edn 2007. Pharmaceutical Press, London United States Pharmacopoeia 29/National Formulary 24 and Supplement 2006 Williamson EM 2002 Potter’s herbal cyclopaedia. CW Daniel Co, Saffron Walden The national pharmacopoeias of many countries and the European Pharmacopoeia; the relevant crude drug monographs of the latter are included in the British Pharmacopoeia 2. Taxonomic Paris RR, Moyse H 1965, 1967, 1971 Matière médicale. Masson, Paris, 3 vols Thoms H 1929 Handbuch der Pharmacie. Urban and Schwarzenberg, Berlin, Band V, 2 vols, Pharmacognosy Trease GE, Evans WC 1972 Pharmacognosy, 10th edn. Baillière Tindall and Cassell, London 3. Morphological Berger F Handbuch der Drogenkunde. Maudrich, Vienna, Vol I, Barks and flowers, 1949; Vol II, Leaves, 1950; Vol III, Fruits and woods, 1952; Vol IV, Herbs, 1954; Vol V, Roots, 1960; Vol VI, Resins etc and seeds, 1964; Vol VII, Index, 1967 Jackson BP, Snowdon DW 1990 Atlas of microscopy of medicinal plants, culinary herbs and spices. Belhaven Press, London Wallis TE, 1967 Textbook of pharmacognosy, 5th edn. Churchill Livingstone, London 4. Pharmacological or Therapeutic Der Marderosian A, Liberti LE 1988 Natural product medicine. GF Stickley, Philadelphia, PA, USA Heinrich M, Barnes J, Gibbons S, Williamson EM 2004 Pharmacognosy and phytotherapy. Churchill Livingstone, Edinburgh Pratt R, Youngken HW, Jr 1956 Pharmacognosy, 2nd edn. Lippincott, Philadelphia, PA, USA Ross MSF, Brain KR 1977 An introduction to phytopharmacy. Pitman Medical, Tunbridge Wells 5. Chemical Bruneton J 1999 Pharmacognosy, phytochemistry, medicinal plants. Intercept Scientific, Medical and Technical Publications Dewick PM 2002 Medicinal natural products, a biosynthetic approach, 2nd edn. John Wiley, Chichester Hänsel R, Sticher O, Steinegger E 1999 Pharmakognosie-Phytopharmazie, 6th edn. Springer, Berlin (in German) Robbers JE, Speedie MK, Tyler VE 1996 Pharmacognosy and pharmacobiotechnology. Williams & Wilkins, Baltimore Tschirch A Handbuch der Pharmakognosie. Tauchnitz, Leipzig (two editions and numerous volumes up to 1933) With the increase in interest in medicinal plants world-wide there are now many publications covering regional areas of the globe. Treatment of the plants in these works may be on any of the above lines. Some examples are given following the Introduction to Part VI. As mentioned previously, a number of bodies have implemented research and published monographs on medicinal herbs. The aim has been to set standards for quality, efficacy and safety in order that the many traditional herbs meet legal requirements. The following are of note: German Commission E monographs.
These were developed for the German Federal Health Authority between 1978–1994 and involve 324 herbs used in German traditional medicine. The monographs give sources, constituents and considerable pharmacological and clinical information. They have now been translated into English and pub- lished by the American Botanical Council in 1999 as a single work followed by expanded monographs in 2000. ESCOP monographs. ESCOP (European Scientific Cooperative for Phytotherapy) is an affiliation of European associations which has produced 60 monographs on herbal drugs, published in loose-leaf form in six fascicules, harmonizing the standards for these drugs through- out the European Union. Information is given on approved therapeutic uses, and unlike the Commission E monographs, provides references.
The second edition of ESCOP Monographs was published in 2003, and a third edition is in the course of preparation. AHP monographs. The American Herbal Pharmacopoeia (1997– 2005) has monographs on a selection of traditional indigenous herbs with some overlap with the European monographs. Treatment of individual drugs can be extensive, for example, the St John’s wort monograph published in HerbalGram 1997, No 4 extends to 32 pages with over 150 references, colour photographs and chemical formulae. WHO monographs.
The World Health Organization published Volume 1 of its Monographs on Selected Medicinal Plants in 1999. It contains standards for quality of drugs together with a therapeutic sec- tion; 31 plant species, the majority of which are also included in the above lists, are considered. Volume 2 was published in 2002. USP monographs.
The United States Pharmacopoeia is also pro- ducing herbal monographs. Eleven have been published, all involving drugs treated above, and twelve more were expected during 2000. Current awareness. Students wishing to read original research will find many references in this book and should learn how to find simi- lar ones for themselves. As no one can hope to read all the scientificliterature that is published, special journals are devoted to the publica- tion of brief abstracts from the original papers. Such abstracts give the author’s name, the subject of the research, the reference necessary to locate the paper in the original journal and usually a brief outline of the work it contains.
Most pharmacy department libraries contain Chemical Abstracts and Biological Abstracts, which in the appropriate sections cover all areas of pharmacognosy. Even so, the systematic searching of the abstracts to cover a broad field of interests can itself be most time-consuming, and publications such as Chemical Titles and Current Contents can be used to give a more rapid indication of recent publica- tions. Phytotherapy Research regularly includes a selected bibliography relating to plant drugs. Information storage and retrieval is now itself a science, and a glance at the shelf-space occupied by succeeding years of Chemical Abstracts is sufficient to indicate that before long, if not already, manual searches of the literature will become impossibly long procedures. In many libraries, hard copies of these publications and of the journals mentioned below are no longer available, but they can be accessed on-line.
Inevitably it will be necessary to rely on databases for literature scanning. Pharmacognosy Titles is a computer abstract coverage of phytochemical research publications up to 1974 (10 vols) produced under the direction of Professor N. Farnsworth, University of Illinois. Subsequently, Farnsworth introduced NAPRALERT, a Natural Product Database which is mainly, but not entirely, post-1975 and is viewed by many as a logical and indispensable collection of pharma- cognostic information. The NAPRALERT database is available on a scheduled-fee basis to scientists, industrial firms, government agencies and academic institutions.
Among other useful databases having a rel- evance to pharmacognosy and published on the Web are MEDLINE, compiled by the US National Library of Medicine and EMBASE, pro- duced by Excerpta Medica. Some journals—for example, Planta Medica, Journal of Ethno- pharmacology, Phytochemistry and Journal of Natural Products— periodically contain reviews on some aspect of medicinal plants. Other journals containing research papers of pharmacognostical interest are Natural Product Research and Natural Product Sciences. Periodical publications appearing in bound form and devoted to reviews on certain aspects of plant constituents are useful for updating; often the reviews cover only the advances in a particular field since the previous volume.
Examples are Natural Product Reports (six issues per year) and Alkaloids (Academic Press).
A series of multi-author books Medicinal and Aromatic Plants – Industrial Profiles (R. Hardman, series editor, CRC Press, Boca Raton, FL) provides an in-depth coverage of major medicinal and aromatic plants for specific genera; to date (2007) forty-five volumes have been published. Individual books for appropriate drugs are cited in Part 5 under ‘Further reading’. Books that are not part of a series but, like the above, multi-author and dealing with certain specialized areas (e.g. alkaloids, flavonoids, isoprenoids), continually appear and generally give up-to-date information (in so far as any book can). Symposia which cover various aspects of pharmacognosy are frequently held in various parts of the world and scientists can easily become acquainted with others having like interests. Often the informal discussions which invariably arise at such meetings can be an extremely useful means of disseminating information. In addition, the lectures presented at such meetings are often subsequently published in book form.
Modern communication systems make world-wide contact between research- ers much simpler. Now available to Western scientists interested in oriental medicine is the quarterly journal Abstracts of Chinese Medicine, published by the Chinese University of Hong Kong. This gives abstracts in English of significant Chinese research papers from more than one hundred scientific journals not readily available outside China.
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