α-Glucosidase Inhibitory Activity of the New Compounds from the Marine-Derived Fungus Meira sp.

Abstract

The strain Meira sp. 1210CH-42 was isolated from a seawater sample. Five secondary metabolites were purified from the fermentation broth of the strain 1210CH-42, including one new citiolone derivative (1) and two new steroids (3, 5). Their structures were elucidated by the comprehensive spectroscopic data analysis of NMR spectra and HR-ESIMS data. The absolute configurations of the compounds were clearly determined based on ECD calculations, and the pyridine-induced deshielding effect. The structure of 5 was confirmed through the oxidation of 3 to produce semi-synthetic 5. These compounds demonstrated anti-diabetes activity. The evaluation of anti-diabetes activity was performed using α-glucosidase colorimetric assays. The new compound 3 exhibited the highest inhibitory effect (IC50 = 86.05 μM). Compounds 2 and 4 showed weaker activities but were more effective than the positive control (acarbose, IC50 = 418.9 μM).