Triterpene saponins from Randia formosa.

ABSTRACT

Seven new triterpenoid saponins, randiasaponins I (1), II (2), III (3), IV (4), V (5), VI (6) and VII (7) as well as two known ones, ilexoside XXVII (8) and ilexoside XXXVII (9), were isolated from the methanolic extract of the leaves of Randia formosa. The structures of the new saponins were established as 3-O-alpha-L-arabinopyranosyl-3 beta,19 alpha,23-trihydroxyursa-12,20(30)-dien-28-oic acid 28-beta-D-glucopyranosyl ester (1), 3-O-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranosyl rotundic acid (2), 3-O-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranosyl pomolic acid 28-beta-D-glucopyranosyl ester (3), 3-O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl pomolic acid 28-beta-D-glucopyranosyl ester (4), 3-O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl siaresinolic acid 28-beta-D-glucopyranosyl ester (5), 3-O-alpha-L-arabinopyranosyl ilexosapogenin A 28-beta-D-glucopyranosyl ester (6), and 3-O-beta-D-glucopyranosyl ilexosapogenin A 28-beta-D-glucopyranosyl ester (7), based on spectral and chemical evidence. Besides the saponins, two common flavonoids kaempferol 3-O-rutinoside and rutin were also isolated.