Extinction of medicinal plants threatens drug discovery
The importance of plants in the search for cancer drugs, and the threat to these plants as highlighted by BGCI, has been discussed recently in an article in the Journal of the National Cancer Institute (Volume 100, Issue 12). For an extract of the article click here.
Current cancer therapeutics include paclitaxel, isolated from the Pacific yew; camptothecin, derived from the Chinese 'happy tree' (Camptotheca acuminata); combretastatin, derived from the South African bush willow; and etoposide from Podophyllum spp., found in the eastern US and Himalayas.
South African bush willow (Combrestatin spp.).
Combrestatin compounds, originally isolated
in the stem bark, are used to curtail the flow
of blood to tumours.
Though the search for anti-cancer drugs from natural products has a long history, for example the discovery of the vinka alkaloids from Catharanthus roseus in the 1950s, the development of new biotechnological methods during the 1990s meant that the interest in natural product research waned, since exploratory screening is both time-consuming and expensive.
Recently however, attention is turning back to natural products as drug sources, since they have been so successful in the past. Modern medcine depends on biological materials as an incomparable source of molecular diversity.
Against this backdrop, almost half the world's plant species may be threatened with extinction; cures as yet undiscovered may exist in plants as yet undescribed - and which may never be described.
Promising drug sources are also found in the sea - sponges, sea squirts and algae for example, are all sources of drugs undergoing clinical studies. Plants are the structural anchors of the ecosystems in which these organisms live. The rapid loss of plant life has far-reaching consequences, and their loss will adversly affect future cancer drug discovery.