Standardization and evaluation of botanical mixtures: lessons from a traditional Chinese herb, Epimedium, with oestrogenic properties.

Botanical extracts differ from conventional supplements in that they are complicated mixtures of many bioactive compounds. Here we describe our experience with a traditional Chinese medicinal plant Epimedium sp. to illustrate the scientific challenges of firstly, obtaining a standardized product from a complex mixture and secondly, evaluating that product for preclinical and clinical efficacy. In contrast, to its colloquial name 'Horny goat weed' and Internet advertisements as a herbal 'Viagra' for men, extracts of Epimedium are strongly oestrogenic due to the presence of novel potent phytoestrogens of the prenyl-flavone family. Since Epimedium is not cultivated, it was necessary to source for taxonomically identified samples and to authenticate their species by phylogenetic, chemical and bioresponse profiling. The feasibility of using a panel of oestrogen-responsive cell-based bioassays to measure summated oestrogenic effects at close time points for pharmacokinetic/pharmacodynamic (PK/PD) modelling was evaluated. We document proportionate oestrogenic responses in sera of animals fed oestrogenic drugs and botanical extracts, indicating that these target molecule responsive cell-based bioassays may have utility to capture the global effects of the myriad bioactive compounds in botanical extracts, informing the design of rigorous clinical trials for safety and efficacy.