New triterpenoid glycosides from Centella asiatica

Four new triterpenoid glycosides named asiaticoside C (1), D (2), E (3), and F (4) were isolated from the BuOH fraction of the EtOH extract of whole plants of Centella asiatica, together with three known compounds, asiaticoside (5), madecassoside (6), and schelfuroside B (7). Based on FAB-MS, IR, H-1- and C-13-NMR, and 2D-NMR data (HMQC, HMBC, COSY), the structures of the new compounds were determined as (2alpha,3beta,4alpha)-23-(acetyloxy)-2,3-dihydroxyurs-12-en-28-oic acid O-alpha-L-rhamnopyranosyl-(1-->4)-O-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl ester (1), (2alpha,3beta)-2,3-dihydroxyurs-12-en-28-oic acid O-alpha-L-rhamnopyranosyl-(1-->4)-O-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl ester (2), asiatic acid 6-O-beta-D-glycopyranosyl-beta-D-glucopyranosyl ester (3), (3beta,4alpha)-3,23-dihydroxyurs-12-en-28-oic acid O-alpha-L-rhamnopyranosyl-(1-->4)-0-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl ester (4).