Leonticins A-C, three octasaccharide saponins from Leontice kiangnanensis

Three octasaccharide saponins, leonticins A, B, and C (1-3), were isolated from the tubers of Leontice kiangnanensis. Their structures were elucidated by a combination of chemical degradation and spectral methods including negative FABMS and NMR measurements as 3-O-beta-D-glucopyranosyl (1-->2)-alpha-L-arabinopyranosylhederagenin 28-O-alpha-L-rhamnopyranosyl (1-->4)-beta-D-glucopyranosyl (1-->6)-beta-D-glucopyranosyl(1-->4)-alpha-L-rhamnopyranosyl (1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside (1), 3-O-[beta-D-xylopyranosyl(1-->3)-beta-D-galactopyranosyl(1-->4)-beta-D- glucopyranosyl (1-->3)][beta-D-glucopyranosyl(1-2)]-alpha-L-arabinopyranosyloleanoli c acid 28-O-alpha-L-rhamnopyranosyl (1-->4)-beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranoside (2), and 3-O-[beta-D-xylopyranosyl (1-->3)-beta-D-galactopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->3)] [beta-D-glucopyranosyl(1-->2)]-alpha-L-arabinopyranosylechinocystic++ + acid 28-O-alpha-L-rhamnopyranosyl(1-->4)-beta-D-glucopyranosyl- (1-->6)-beta-D-glucopyranoside (3), respectively. The complete assignments of the proton and carbon resonances for 1-3 were achieved based on extensive 2D NMR analysis (DQF-COSY, TOCSY, ROESY, HSQC, and HMBC).