The value of central-African traditional medicine for lead finding: Some case studies

Ethnoparmaological relevance: One of the possible methodologies for the discovery of novel drugs is the screening of selected plant extracts for a broad array of pharmacological activities.

The selection based on enthnomedicinal uses, combined with a follow-up of existing literature on the plants' chemotaxonomic properties, would seem to be the most cost-effective strategy for finding active plant extracts. A bioassay-guided fractionation of the active extracts should subsequently lead to the isolation and identification of the active lead constituent(s).

Taking into account the enormous number and the amazing structural diversity of the currently known plant constituents, one might hope that promising model compounds with new structures and/or novel mechanisms of action might be found. In order, however, to optimize such a natural product drug discovery methodology, dereplication and selectivity of activity should be included in the screening system. Dereplication by which known compounds can rapidly be identified from a partially purified mixture prevents a research group from wasting resources by rediscovering known compounds. The use of single-target specific bioassays such as tests on isolated enzymes or on receptor-binding, or multiple target functional bioassays on isolated organs or intact cells must allow at an early stage to isolate compounds with specific pharmacological properties.

In this publication, several examples of bioassay-guided isolation and identification of pharmacologically active lead compounds from plants used in Central-African traditional medicine by our research group will be presented and discussed.