New antioxidant and antiglycation active triterpenoid saponins from the root bark of Aralia taibaiensis.

Four new oleanane type triterpenoid saponins (1-4) and a known saponin (5) were isolated from the root bark of Aralia taibaiensis Z.Z. Wang et H.C. Zheng. The structures of the four new compounds were elucidated as 3-O-{β-D-glucopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→3)]-β-D-glucurono-pyranosyl}-olean-11,13(18)-diene-28-oic acid 28-O-β-D-glucopyranosyl ester (1), 3-O-{β-D-gluco-pyranosyl-(1→3)-[α-l-arabinofuranosyl-(1→4)]-β-D-glucuronopyranosyl}-olean-11,13(18)-diene-28-oic acid 28-O-β-D-glucopyranosyl ester (2), 3-O-{β-d-glucopyranosyl-(1→2)-[α-l-arabinofuranosyl-(1→4)]-β-D-glucuronopyranosyl}-oleanolic acid 28-O-β-D-glucopyranosyl ester (3) and 3-O-{β-D-glucopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→3)]-β-D-glucuronopyranosyl}-oleanolic acid 28-O-β-D-glucopyranosyl ester (4), on the basis of extensive spectral analysis and chemical evidence. Compounds 1-5 exhibited moderate effects on antioxidant and antiglycation activities, which correlated with treatment of diabetes mellitus.