The Pharmaceutical Journal
Vol 269 No 7208 p139
27 July 2002

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Pharmacognosy and natural products

‘Trease and Evans pharmacognosy’, 15th edition, by William Charles Evans. Pp xiii+585. Price £59.95. London: Elsevier Science; 2002. ISBN 0 7020 26174.

Trease and Evans pharmacognosy is a stalwart pharmacognosy text, and one that continues to bring fresh material to each edition. This new edition also comprises larger pages, clearer fonts, and an improved page layout which, altogether, significantly enhance the presentation of the text, chemical structures, figures and so on.

It has been extensively revised in line with the continuing interest and developments in the use of plants as medicines and in plants as sources of new drugs. There is a new chapter on production of crude drugs which discusses factors such as environmental conditions, cultivated versus wild plants, collection, drying, storage and other factors that can influence the profile and concentration of active constituents in plant material. A particular strength of the book is the extensive (300 pages), comprehensive section "Pharmacopoeial and related drugs of biological origin" which, for example, includes a 60-page chapter on alkaloids.

The book continues to include specialist chapters by invited authors, and these, particularly the one on antiprotozoal compounds, have been updated to some extent. There are also several invited chapters which are new for this edition. These include an interesting, albeit short, chapter on commerce in crude (plant) drugs that outlines historical developments and provides an insightful account of current issues, such as changing supply patterns.

There is an excellent chapter on synergy and polyvalent action in herbal medicinal products — what these terms mean, how they can be measured, and what evidence there is of both enhancement of activity and attenuation of toxicity in various medicinal plants.

Another new chapter describes traditional plant medicines as sources of new drugs, reflecting the importance of "ethnic" or "cultural" use of plant remedies in the discovery of novel pharmaceuticals. The chapter describes this ethnopharmacological approach to drug discovery, provides several examples of newer compounds that have emerged from this process, and also considers its limitations. The use of high throughput screening in the discovery of new lead compounds from plants is also the subject of a new chapter.

This 15th edition continues to recognise the importance of, and sustained public interest in and demand for, "alternative" systems of medicine, such as Chinese, Asian and African traditional medicine, which use plant-based preparations in their treatments. Several chapters provide good summaries of these systems, with a focus on composition and activities of substances used and, to a lesser extent, some issues relevant to pharmacy, such as the legal background to "western" herbal medicines and those included on the general sales list.

In my view, the effort that has gone into this new edition of Trease and Evans illustrates the continuing contribution that plants make to the development of pharmaceuticals and thus the importance of pharmacognosy and natural products in pharmacy.

Jo Barnes