Historically, drug discovery has focused on the identification of a single constituent responsible for the activity of a plant. This approach has led to the discovery of a wide variety of plant-derived drugs, such as digoxin (from foxglove, Digitalis purpurea), vinblastine (from to periwinkle, Vinca minor), and taxol (from Pacific yew,Taxus brevifolia). Over the past decade, though, as the popularity of alternative medicine in the US has increased, there has been more research into the efficacy of whole plant extracts as opposed to isolated constituents. Proponents of the use of herbals suggest that their complex composition yields enhanced efficacy due to synergistic interactions among multiple components. However, this complexity makes research correlating chemical composition of extracts with biological activity extremely challenging. The Cech research group addresses this problem with the use of sophisticated analytical instrumentation, which facilitates detailed characterization of the constituents of complex plant extracts. This chemical characterization, combined with various assays of biological activity, give us insight into how complex mixtures of plant compounds interact within the human body.