Screening for Anti-lipase Properties of 37 Traditional Chinese Medicinal Herbs

Background: To find new, crude anti-obesity drugs from natural sources through the inhibition of adsorption of dietary lipids, in vitro porcine pancreatic lipase (PPL; triacylglycerol lipase, EC 3.1.1.3) inhibitory tests were carried out on selected plants with weight-reducing or related potential, used in Chinese traditional medicine. Methods: The methanolic extracts of 37 traditional Chinese herbal medicines of different families were assayed for their in vitro activity against PPL by using spectrophotometry with 2,4-dinitrophenyl butyrate as a synthetic substrate. Coexistent phytochemicals, or those present in high levels, in the 3 most promising Chinese herbs were tested for their anti-lipase activity. Results: Extracts from 2 herbs, Prunella vulgaris L. (Labiatae) and Rheum palmatum L. (Polygonaceae), at a concentration of 200 mu g/mL, significantly inhibited PPL-by 74.7% and 53.8%, respectively. Quercetin exhibited better activity (27.4%) than all the other phytochemicals at a final concentration of 25 mu g/mL in the assay system, followed by luteolin, with an activity of 17.3%. Conclusion: The results support the view that herbs represent a rich source of anti-lipase compounds. The screening of the methanolic extracts of 37 Chinese medicinal plants in vitro led to the identification of several extracts with potential activity against PPL, in particular, P vulgaris and R. palmatum. We also found that several monomeric chemicals in these herbs exhibited good or moderate activity against PPL. To the best of our knowledge, these traditional Chinese herbal medicines or phytochemicals have not been previously screened for their lipase inhibitory activity. [J Chin Med Assoc 2010;73(6):319-324]