Triterpenoid saponins from stem bark of Pentaclethra macroloba

two new and two known triterpenoid saponins were isolated from the stem bark of pentaclethra macroloba. their structures were determined using a combination of homo- (1d 1h nmr, 13c nmr-hbbd and 13c nmr-dept) and heteronuclear 2d nmr techniques (1h-1h-cosy, 1h-1h-tocsy, 1h-1h-noesy, hmqc and hmbc), esims and chemical methods. the structures of the two new pentacyclic triterpenoid saponins were established as 3b-o-{[b-d-glucopyranosyl-(1？3)-a-l-rhamnopyranosyl-(1？2)],b-d- glucopyranosyl-(1？4)}-a-l-arabinopyranosylhederagenin (3) and 3b-o-{[b-d-glucopyranosyl-(1？4)-b-d-glucopyranosyl-(1？3)-a-l-rhamnopyranosyl- (1？2)],b-d- glucopyranosyl(1？4)}-a-l-arabinopyranosyloleanolic acid (4).