Two novel enantiomers from metarhizium flavoviride and their inhibitory activities against α-glucosidase

A pair of novel enantiomers metarrhiziumoids A (R-enantiomer, 14.3 mg) and B (S-enantiomer, 9.5 mg) were isolated from 3.0 g extract of Metarhizium flavoviride by silica gel column chromatography combined with preparative and semi-preparative HPLC, and identified with high resolution mass, 1D, 2D NMR and circular dichroism. Targets prediction showed that the two compounds had glycosidase inhibitory activity. Result of alpha-glycosidase inhibitory tests showed that the both enantiomers were competitive inhibitors of alpha-glycosidase, and the bioactivity of metarrhiziumoids B (IC50 = 174 mu g/mL) was stronger than that of metarrhiziumoids A (IC50 = 259 mu g/mL). Molecular docking results show that the two enantiomers have different optimal docking modes and the binding energy for the S-enantiomer (-7.8 kcal/mol) was lower than for the R-enantiomer (-7.20 kcal/mol). The docking mode selections and binding energy differences resulted in the inhibitory activity difference. (c) 2022 Elsevier B.V. All rights reserved.