Natural products isolation in modern drug discovery programs.

Natural products play a vital role in drug discovery. They have served as the basic reference and initiators in drug discovery programs. Natural products as pure compounds have been involved in western medicine as drugs or lead compounds for drug discovery and development. In traditional medicine, they have been involved for a very long time as medicinal extracts, infusions, decoctions, or other therapeutic preparations. Modern drug discovery programs require an arsenal of drug candidate molecules in pure form whose activities (usually against cells or enzymes) are rapidly determined using high-throughput screening (HTS) and activities are expected in micro- (μM) to nanomolar (nM) levels. The difficulty in meeting today's standards for drug candidate molecules poses the question: are natural products still relevant in modern drug discovery programs? This and other issues, including the spectroscopic investigation of crude extracts, are discussed.