Thiolactones and Δ 8,9 -Pregnene Steroids from the Marine-Derived Fungus Meira sp. 1210CH-42 and Their α -Glucosidase Inhibitory Activity

The fungal genus was first reported in 2003 and has mostly been found on land. This is the first report of second metabolites from the marine-derived yeast-like fungus sp. One new thiolactone ( ), along with one revised thiolactone ( ), two new Δ -steroids ( , ), and one known Δ -steroid ( ), were isolated from the sp. 1210CH-42. Their structures were elucidated based on the comprehensive spectroscopic data analysis of 1D, 2D NMR, HR-ESIMS, ECD calculations, and the pyridine-induced deshielding effect. The structure of was confirmed by oxidation of to semisynthetic . In the -glucosidase inhibition assay, compounds - showed potent in vitro inhibitory activity with IC values of 148.4, 279.7, and 86.0 μM, respectively. Compounds - exhibited superior activity as compared to acarbose (IC = 418.9 μM).