Four new triterpene saponins from the seeds of Aesculus chinensis

Two pairs of new geometrically isomeric triterpenoid saponins were isolated from the seeds of Aesculus chinensis and characterized as 28-acetyl-21-tigloylprotoaescigenin 3-O-beta-D-xylopyranosyl (1 --> 2)] beta-D-glucopyranosyl (1 --> 4)] beta-D-glucopyranosiduronic acid (isoescin IIa, 1) and 28-acetyl-21-angeloylprotoaescigenin 3-O--beta-D-xylopyranosyl (1 --> 2)] beta-D-glucopyranosyl (1 --> 4)] beta-D-glucopyranosiduronic acid (isoescin IIb, 2); 28-acetyl-21-tigloylbarringtogenol C 3-O-beta-D-galactopyranosyl (1 --> 2)] beta-D-glucopyranosyl (1 --> 4)] beta-D-glucopyranosiduronic acid (isoescin IIIa, 3) and 28-acetyl-21-angeloylbarringtogenol C 3-O-beta-D-galactopyranosyl (1 --> 2)] beta-D-glucopyranosyl (1 --> 4)] beta-D-glucopyranosiduronic acid (isoescin IIIb, 4). Their structures were established on the basis of spectroscopic and chemical evidence.