Triterpene glycosides from the bark of Robinia pseudo-acacia L. I

From the bark of Robinia pseudo-acacia L., five new triterpene glycosides, robiniosides A-D (3, 5-7) and compound III (4), were isolated and their structures were elucidated as 3-O-alpha-L-rhamnopyranosyl(1-->2)-beta-D-glucopyranosyl(1-->2)-beta-D- glucuronopyranosyl 3 beta,22 beta-dihydroxyolean-12-en-29-oic acid (3), 3-O-alpha-L-rhamnopyranosyl(1-->2)-beta-D-galactopyranosyl(1-->2)-beta-D -glucuronopyranosyl 3 beta,22 beta,24-trihydroxyolean-12-en-29-oic acid (4), whose sapogenol was unambiguously characterized and designated as oxytrogenin, 3-O-alpha-L-rhamnopyranosyl(1-->2)-beta-D-glucopyranosyl(1-->2)-beta-D glucuronopyranosyl oxytrogen (5), 3-O-alpha-L-rhamnopyranosyl(1-->2)-beta-D galactopyranosyl(1-->2)-beta-D-glucuronopyranosyl oxytrogenin 22-O-alpha-L-rhamnopyranoside (6), 3-O-alpha-L- rhamnopyranosyl(1-->2)-beta-D-glucopyranosyl(1-->2)-beta-D-glucuronop yranosyl oxytrogenin 22-O-alpha-L-rhamnopyranoside (7), respectively, together with two known triterpene glycosides, kaikasaponin III (1) and 3-O-alpha-L-rhamnopyranosyl(1-->2)-beta-D-galactopyranosyl(1-->2)-beta-D - glucuronopyranosyl 3 beta,22 beta-dihydroxyolean-12-en-29-oic acid (2).