Research and future trends in the pharmaceutical development of medicinal herbs from Chinese medicine.

Issues concerning the past and future development of medicinal herbs from Chinese medicine (CM) are addressed in this paper. In the Western world, medicinal herbs are becoming increasingly popular and important in the public and scientific communities. In contrast to their regulated status in China and other countries, herbal medicines are regarded as dietary supplements in the US. Accordingly, research must continue worldwide to identify and improve the efficacy of the active principals of herbs both singly and in combination -- from active ingredients, active fractions, and active herbal formulations. While Western medicine currently employs pure, single compounds, either natural or synthetic, CM has long used multiple combinations of compounds in the form of processed natural products, primarily medicinal herbs, to treat and relieve the symptoms of many different human diseases. CM may have fewer and less severe side effects than single pure drugs, making CM especially attractive to the consumer. In effect, CM's focus on combination therapy does serve both ancient and modern theories. However, research using modern analytical and chemical techniques is needed to ensure efficacy and safety, to provide qualitative and quantitative analyses for dietary supplements, and to develop new, effective and safe world-class drugs. Drug design is an iterative process. Bioactivity-directed fractionation and isolation identify active natural compounds from single herbs or formulations. These lead structures can be chemically modified and improved through knowledge of structure--activity relationship, mechanism of action, drug metabolism, molecular modelling and combinatorial chemistry studies. Finally, efficacy and toxicity determination as well as clinical trials can contribute to the generation of new drugs from CM. To continue the legacy of CM, as well as the worldwide uses of other medicinal herbs, continued investigation of active formulations, bioactive fractions, and isolated compounds is critical to drug development in the 21st century.