α-Glucosidase Inhibitors: Diphenyl Ethers and Phenolic Bisabolane Sesquiterpenoids from the Mangrove Endophytic Fungus Aspergillus flavus QQSG-3

摘要

Two new diphenyl ethers (>1 and >2) and four new phenolic bisabolane sesquiterpenoids (>3–>6), together with five known related derivatives, were isolated from the culture of the endophytic fungus Aspergillus flavus QQSG-3 obtained from a fresh branch of Kandelia obobata, which was collected from Huizhou city in the province of Guangdong, China. The structures of compounds >1–>6 were determined by analyzing NMR and HRESIMS data. The absolute configurations of >5 and >6 were assigned by comparing their experimental ECD spectra with those reported for similar compounds in the literature. All isolates were evaluated for their α-glucosidase inhibitory activity, of which compounds >3, >5, >10, and >11 showed strong inhibitory effects with IC50 values in the range of 1.5–4.5 μM.