Synergy in natural medicines: implications for drug discovery.

To overcome the ‘more investments, less drugs’ challenge in drug development [1], more and more medicinal chemists turn their attention to natural medicines in an attempt to find new-entity drugs from an unexplored chemical space [2]. Although some promising drugs and candidates have been derived from natural medicines in recent years [2], it should be kept in mind that it is a great challenge to find single-component new-entity drugs from these medicines because the efficacy of most natural medicines lies in the synergy of diverse components rather than a single compound [3].