Bioactive glycosides from Salacia cochinchinensis

Four new triterpene glycosides, named salaciacochinosides A-D (1-4) were isolated from the 90% ethanol extract of Salacia cochinchinensis, together with five known compounds 2α,3β,23-trihydroxyurs-12,18-dien-28-oic acid 28-O-β-d-glucopyranoside (5), racemiside (6), alangiplatanoside (7), acantrifoside E (8), and syringin (9). The structures of the four new triterpenoids were characterized by chemical methods and MS, IR, 1D and 2D NMR spectral analyses. The α-glucosidase inhibitory activities of the nine compounds were assessed, compounds 6 and 7 showed remarkable α-glucosidase inhibitory activities, with IC₅₀ values of 0.44 and 0.75 μM, respectively. Compounds 1-5 exhibited moderate α-glucosidase inhibitory activities, and compounds 8 and 9 showed none α-glucosidase inhibitory activity in our current experiments.