African medicinal plants in the search for new drugs based on ethnobotanical leads

In the African world view the natural environment is a living entity whose components are intrinsically bound to mankind. Dietary plants, spices and common herbs dominate the materia medica, in contrast with modern orthodox medicine which uses many regulated poisons. Drug development based on ethnobotanical leads has followed two paths: the classical approach of identification of single plant species with biologically active compounds and the characterization and standardization of traditional recipes for reformulation as medicines. The first approach has led to the recognition of many African plants as medicines and the isolation of several biologically active molecules; examples range from the well physostigmine (from Physostigma venonosum) used for the treatment of glaucoma to the recently identified antiviral agents from Ancistrocladus abbreviatus. The second approach which aims at optimization of mixed remedies as formulated dosage forms is perhaps more relevant to the needs of the poor rural populations but has remained largely ignored. Drug development programmes based on ethnobotanical leads must provide for just and fair compensation for individual informants and local communities.