Triterpenoid saponins from Aster auriculatus

Three new triterpenoid saponins (1-3), together with one known saponin scaberoside B-6 methyl ester (4) were isolated from an ethanol extract of roots of Aster auriculatus. The structures of 1-3 have been determined on the basis of spectral and chemical evidence as 3-O-beta-D-glucuronyl-16 alpha-hydroxy-olean-12-en-28-oic acid 28-O-[alpha-L-arabinopyranosyl(1-->4)-alpha-L-rhamnopyranosyl(1-->3)]-alpha-L-arabinopyranoside (1-->2)]-[beta-xylopyranosyI(1-->3)-beta-D-xylopyranosyl(1-->3)]-alpha-L-arabinopyranoside (1), the methyl ester of 3-O-beta-D-glucuronyl-16 alpha-hydroxy-olean-12-en-28-oic acid acid 28-O-[beta-D-xylopyranosyl(1-->3)-alpha-L-arabinopyranosyl(1-->4)]-[beta-D-apiofuranosyl(1-->3)]-alpha-L-rhamnopyranosyl(1-->2)-beta-D-xylopyranoside (2), and 3-O-beta-D-glucuronyl-olean-12-en-28-oic acid 28-O-beta-D-xylopyranosyl(1-->3)-beta-D-xylopyranosyl(1-->4)-alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside (3).