A new flavan-3-ol lactone and other constituents from Euonymus alatus with inhibitory activities on α-glucosidase and differentiation of 3T3-L1 cells.

Bioassay-guided fractionation, based on inhibition of α-glucosidase, of Euonymus alatus led to the isolation of a new compound, catechin lactone A (7), and seven known compounds (1-6 and 8). Their structures were established on the basis of extensive 1D- and 2D-NMR experiments. The absolute configurations of compound 7 have been determined using vibrational circular dichroism spectroscopy. All these compounds were evaluated for their inhibition activities on α-glucosidase and differentiation of 3T3-L1 cells. Compounds 1, 3-5, 7 and 8 showed potent yeast α-glucosidase inhibition with IC50 values of 119.1, 39.6, 31.6, 23.0, 71.8 and 102.5 µM, respectively; compounds 3-5, 7 and 8 can remarkably inhibit the differentiation of 3T3-L1 pre-adipocytes. This is the first report about α-glucosidase and 3T3-L1 inhibitory activities of compounds 3, 7 and 8.