Bergamotane Sesquiterpenes with Alpha-Glucosidase Inhibitory Activity from the Plant Pathogenic Fungus Penicillium expansum

Two new bergamotane sesquiterpene lactones, named expansolides C and D (1 and 2), together with two known compounds expansolides A and B (3 and 4), were isolated from the plant pathogenic fungus Penicillium expansum ACCC37275. The structures of the new compounds were established by detailed analyses of the spectroscopic data, especially 1D-, 2D-NMR, and HR-ESI-MS. In an in vitro bioassay, the epimeric mixture of expansolides C and D (1 and 2) (in a ratio of 2:1 at the temprature of the bioassay) exhibited more potent -glucosidase inhibitory activity (IC50 =0.50 +/- 0.02 mm) as compared with the positive control acarbose (IC50 = 1.90 +/- 0.05 mm). To the best of our knowledge, it was the first report on the -glucosidase inhibitory activity of bergamotane sesquiterpenes.