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.