Studies on the constituents of Clematis species. VI. The constituents of Clematis stans Sieb. et Zucc

Abstract

From the roots of Clematis stans three new oleanane-type triterpenoid saponins named clemastanoside A, B and C, and two new lignan glycosides named clemastanin A and B, have been isolated together with three known triterpenoid saponins, huzhangoside B, C and D, and three known lignan glycosides, (+)-lariciresinol 4-O-beta-D-glucopyranoside, (+)-lariciresinol 4'-O-beta-D-glucopyranoside and (+)-pinoresinol 4,4'-O-bis-beta-D-glucopyranoside. In addition, from the leaves, four new oleanane-type triterpenoid saponins, named clemastanoside D, E, F and G, have been isolated together with five known triterpenoid saponins, hederasaponin B, kizutasaponin K12, huzhangoside B, sieboldianoside B and huzhangoside D, and three known flavonoids, isoquercitrin, rutin and quercetin 3-O-beta-D-glucuronopyranoside. The structures of the new compounds were elucidated based on chemical and physicochemical evidence as follows: clemastanoside A, 3-O-beta-D-ribopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl-(1-->2)-a lpha-L- arabinopyranosyl oleanolic acid 28-O-(4-O-acetyl)-alpha-L-rhamnopyranosyl-(1-->4)-beta-D- glucopyranosyl-(1-->6)-beta-D-glucopyranosyl ester (terminal rhamnosyl 4-O-acetate of huzhangoside B); clemastanoside B and C, 3-O-beta-D-xylopyranosyl- and 3-O-beta-D-ribopyranosyl-(1-->3)-alpha-L- rhamnopyranosyl-(1-->2)-beta-D-galactopyranosyl oleanolic acid 28-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl- (1-->6)-beta-D-glucopyranosyl ester, respectively; clemastanoside D, 3-O-beta-D-ribopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl- (1-->2)-alpha-L-arabinopyranosyl hederagenin 28-O-beta-D-glucopyranosyl ester; clemastanoside E, F and G, terminal rhamnosyl 4-O-, 3-O- and 2-O-acetate of 3-O-beta-D-ribopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl-(1-->2)-a lpha-L- arabinopyranosyl hederagenin 28-O-alpha-L-rhamnopyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta- D- glucopyranosyl ester, respectively; clemastanin A, (7S,8R)-3-methoxy-3',4,9,9'-tetrahydroxy-4',7-epoxy-5',8-lignan 3'-O-beta-D-glucopyranoside; clemastanin B, (+)-lariciresinol 4,4'-O-bis-beta-D-glucopyranoside.