New inhibitors of α-glucosidase in Salacia hainanensis Chun et How.

The methanol extract from roots of Salacia hainanensis Chun et How afforded three new compounds, 24,26-dihydroxy-25-methoxy-tirucall-9-en-3-one (1), 2β,3β,22α-trihydroxy-lup-20(29)-ene (2) and 3β-hydroxy-2-carbonyl-lupan-29-oic acid (3), along with six known triterpenoids (4-9). Their structures were established on the basis of spectral analysis, in particular according to the data obtained by two-dimensional-NMR and high-resolution mass spectra experiments. Some of them showed much stronger inhibitory activity towards α-glucosidase than the positive control (acarbose, IC₅₀ 10.2 μM).