Butenolide Derivatives with α-Glucosidase Inhibitions from the Deep-Sea-Derived Fungus Aspergillus terreus YPGA10

Three new butenolide derivatives, namely aspernolides N-P (1-3), together with six known analogues (4-9), were isolated from the ethyl acetate (EtOAc) extract of the deep sea-derived fungus Aspergillus terreus YPGA10. The structures of compounds 1-3 were determined on the basis of comprehensive analyses of the nuclear magnetic resonance (NMR) and mass spectroscopy (MS) data, and the absolute configurations of 1 and 2 were determined by comparisons of experimental electronic circular dichroism (ECD) with calculated ECD spectra. Compound 1 represents the rare example of Aspergillus-derived butenolide derivatives featured by a monosubstituted benzene ring. Compounds 6-9 exhibited remarkable inhibitory effects against alpha -glucosidase with IC50 values of 3.87, 1.37, 6.98, and 8.06 mu M, respectively, being much more active than the positive control acarbose (190.2 mu M).