Triterpenoids and meroterpenoids with α-glucosidase inhibitory activities from the fruiting bodies of Ganoderma australe.

ABSTRACT

Macrofungi Ganoderma is a valuable medicinal fungus resource for human health and longevity in China. In this study, ten undescribed compounds including seven lostane-type triterpenoids, ganodaustralic acids A âˆ¼ G (1-7), one pair of meroterpenoid enantiomers, (-)-6'-O-ethyllingzhiol (8) and (+)-6'-O-ethyllingzhiol (9), and one polyhydroxylated sterol, 3-O-acetyl-fomentarol C (10), together with eight known compounds (11-18), were isolated from the fruiting bodies of Ganoderma australe. The structures of the new compounds were elucidated by extensive spectroscopic analysis as well as NMR and electronic circular dichroism (ECD) calculations. Compounds 4, 8, 9, and 12 showed significant α-glucosidase inhibitory activities with IC50 values in the range of 4.1-11.7 µM, which were superior to that of positive control acarbose (213 µM). Only compound 7 exhibited weak cytotoxicity against SGC-7901 cells.