Plant part substitution - a way to conserve endangered medicinal plants?

Population growth, urbanization and the unrestricted collection of medicina l plants from the wild is resulting in an over-exploitation of natural reso urces in southern Africa. Therefore, the management of traditional medicina l plant resources has become a matter of urgency. In southern Africa the mo st frequently used medicinal plants are slow-growing forest trees, bulbous and tuberous plants, with bark and underground parts being the parts mainly utilized. A strategy which would satisfy the requirements of sustainable h arvesting, yet simultaneously provide for primary health care needs, would be the substitution of bark or underground parts with leaves of the same pl ant. This paper outlines the concept of plant substitution, using prelimina ry results of our recent investigations into four of the most important and most threatened South African medicinal plants - Eucomis autumnalis (bulb) . Siphonochilus aethiopicus (rhizome), Ocotea bullata (bark), and Warburgia n salutaris (bark) - as a demonstration of the kind of research necessary. Extracts of various plant parts were compared chemically using TLC-analysis , and pharmacologically in terms of antibacterial activity and cyclooxygena se-1 inhibition in vitro. The importance of the concept of plant part subst itution as a strategy for the conservation of medicinal plants in southern Africa is discussed in terms of the results obtained. (C) 3000 Elsevier Sci ence Ireland Ltd. All rights reserved.