Medicinal foodstuffs. XII. Saponin constituents with adjuvant activity from hyacinth bean, the seeds of Dolichos lablab L. (1): Structures of lablabosides A, B, and C.

Abstract

From the glycoside mixture with adjuvant activity obtained from the hyacinth bean, the seeds of Dolichos lablab L., six new oleanane-type triterpene bisdesmosides, lablabosides A, B, C, D, E, and F, were isolated together with chikusetsusaponin IVa. The structures of lablabosides A, B, and C were determined on the basis of chemical and physicochemical evidence as follows: 3-O-[alpha-L-rhamnopyranosyl (1-->2)-beta-D-galactopyranosyl (1-->2)-beta-D-glucopyranosiduronic acid]-28-O-(beta-D-glucopyranosyl) oleanolic acid (lablaboside A), 3-O-[alpha-L-rhamnopyranosyl (1-->2)-beta-D-galactopyranosyl (1-->2)-beta-D-glucopyranosiduronic acid]-28-O-(beta-D-glucopyranosyl) 24-epi-hederagenin (lablaboside B), 3-O-[alpha-L-rhamnopyranosyl (1-->2)-beta-D- galactopyranosyl (1-->2)-beta-D-glucopyranosiduronic acid]-28-O-[alpha-L-rhamnopyranosyl (1-->2)-beta-D-glucopyranosyl] 24-epi-hederagenin (lablaboside C).