Four new triterpenoid saponins from Ardisia gigantifolia Stapf. and their cytotoxic activity.

Four new oleanane-type triterpenoid saponins, cyclamiretin A 3beta-O-alpha-L-rhamnopyranosyl-(1 --> 3)-[beta-D-xylopyranosyl-(1 --> 2)]-beta-D-glucopyranosyl-(1 --> 4)-[beta-D-glucopyranosyl-(1 --> 2)]-alpha-L-arabinopyranoside (1), cyclamiretin A 3beta-O-alpha-L-rhamnopyranosyl-(1 --> 3)-[beta-D-glucopyranosyl-(1 --> 3)-beta-D-xylopyranosyl-(1 --> 2)]-beta-D-glucopyranosyl-(1 --> 4)-[beta-D-glucopyranosyl-(1 --> 2)]-alpha-L-arabinopyranoside (2), cyclamiretin A 3beta-O-alpha-L-rhamnopyranosyl-(1 --> 3)-[beta-D-xylopyranosyl-(1 --> 2)]-beta-D-glucopyranosyl-(1 --> 4)-[beta-D-6-O-acetylglucopyranosyl-(1 --> 2)]-alpha-L-arabinopyranoside (3) and 3beta-O-[alpha-L-rhamnopyranosyl-(1 --> 3)-[beta-D-xylopyranosyl-(1 --> 2)]-beta-D-glucopyranosyl-(1 --> 4)-[beta-D-glucopyranosyl-(1 --> 2)]-alpha-L-arabinopyranoside]-16,28-dihydroxy-30-acetoxyoleana-12-en (4), along with one known triterpene saponin and ardisiacrispin A (5) were isolated from the rhizome of Ardisia gigantifolia. Their structures were established with the help of extensive spectroscopic techniques. Furthermore, the inhibitory effects of compounds on tumor cells (MTT based) in vitro were evaluated, and compounds 1, 2, and 5 showed potent anti-tumor activities.