Screening of lipase inhibitors in Folium Mori with lipase-linked magnetic microspheres by high-performance liquid chromatography and evaluation in diabetic mice.

A new method for the screening of compounds with hypoglycemic effect from traditional Chinese medicines employing high-performance liquid chromatography and lipase-linked magnetic microspheres has been proposed. We hypothesized that the interaction of traditional Chinese medicine extracts with lipase-linked magnetic microspheres should decrease the concentration of compounds with hypoglycemic effect. Using this approach, the potential lipase inhibitors in Folium Mori extract were investigated. First, lipase was immobilized on magnetic microspheres by a chemical method. Then, by comparing the chromatograms of samples before and after the interaction with lipase-linked magnetic microspheres, seven compounds of Folium Mori extract were identified. It was found that protocatechuic acid, chlorogenic acid, protocatechualdehyde, rutin, isoquercitrin, astragalin, and dicaffeoylquinic acid B had evident combination with lipase-linked magnetic microspheres. Their hypoglycemic effects were verified in streptozocin-induced diabetic mice. In the present study, astragalin was verified to improve the glucose tolerance and lower the level of glucose in streptozocin-induced diabetic mice, which indicated that astragalin might be a new highly efficient lipase inhibitor. Based on these significant results, this method could be a convenient approach to screen potential lipase inhibitors from traditional Chinese medicines. Meanwhile, it also could be expanded to screen other active compounds in traditional Chinese medicines.