Natural Products Drug Discovery

The thrust of my research is natural products drug discovery. We are investigating tropical rainforest plants from locations such as Monteverde, Costa Rica, far north Queensland, Australia, and Matabeleland, Zimbabwe, for potential medicinal utility.

In earlier times, all drugs and medicinal agents were derived from natural substances, and most of these remedies were obtained from higher plants. Today, many new chemotherapeutic agents are synthetically derived, based on "rational" drug design. The study of natural products has advantages over synthetic drug design in that it leads optimally to materials having new structural features with novel biological activity. Not only do higher plants continue to serve as important sources of new drugs, but phytochemicals derived from them are also extremely useful as lead structures for synthetic modification and optimization of bioactivity. The starting materials for about one-half of the medicines we use today come from natural sources. Virtually every pharmacological class of drugs includes a natural product prototype. The future of higher plants as sources of medicinal agents for use in investigation, prevention, and treatment of diseases is very promising.

The purpose of this research is to collect and extract plant materials and then to screen them for potential biological activity (antimicrobial activity, antiviral activity, antitumor activity). Extracts which show potential medicinal utility are subjected to bioactivity-directed fractionation and isolation. The structures of the active components are then elucidated using spectroscopic and crystallographic techniques.

We have found a here-to-fore undescribed Salacia (Hippocrateaceae) liana species from Costa Rica to be especially cytotoxic to a number of tumor cell lines as well as antibacterial to Gram-positive bacteria. The active component from this plant is the nortriterpenoid tingenone.