New butenolide derivatives from the marine sponge-derived fungus Aspergillus terreus.

Two new butenolide derivatives (±)-asperteretal D ((±)-1) and asperteretal E (2) containing rare 2-benzyl-3-phenyl substituted lactone core, together with nine known analogues (3-11) were obtained from a fungus Aspergillus terreus derived from the marine sponge Phakellia fusca. All the structures were elucidated on the basis of extensive NMR spectroscopic data. The chiral chromatography analyses allowed the separation of the (±)-asperteretal D, of which the absolute configurations were determined by comparing the experimental to calculated electronic circular dichroic (ECD) spectra. Compounds (±)-1, 2-5, and 7 exhibited potent inhibitory activities against α-glucosidase with IC50 values ranging from 8.65 to 20.3 µM (positive control acarbose with an IC50 value of 320 µM). In addition, derivatives 5-8 also showed moderate antioxidant activities.