Terpenoids from the Deep-Sea-Derived Fungus YPGA3 and Their Bioactivities.

A chemical study of the ethyl acetate (EtOAc) extract from the deep-sea-derived fungus YPGA3 led to the isolation of a new austalide meroterpenoid () and seven known analogues (), two new labdane-type diterpenoids ( and ) and a known derivative (). The structures of new compounds , , and were determined by comprehensive analyses via nuclear magnetic resonance (NMR) and mass spectroscopy (MS) data. The absolute configurations of , , and were determined by comparisons of experimental electronic circular dichroism (ECD) with the calculated ECD spectra. Compound represented the third example of austalides bearing a hydroxyl group at C-5 instead of the conserved methoxy in other known analogues. To our knowledge, diterpenoids belonging to the labdane-type were discovered from species of for the first time Compound 1 showed cytotoxicity toward MDA-MB-468 cells with an IC value of 38.9 M. Compounds and exhibited inhibition against α-glucosidase with IC values of 910 and 525 M, respectively, being more active than the positive control acarbose (1.33 mM).