Studies on the constituents of the root of Polygala tenuifolia Willdenow. II. On the structures of onjisaponins A, B and E.

The structures of three triterpenoidal saponins, onjisaponins A (1), B (2) and E (3), were determined on the basis of spectral and chemical evidence as presenegenin-(3)-β-D-glucopyranosido-(28)-2-O-{[β-D-apio-D-furanosyl (1→3)] [β-D-galactopyranosyl (1→4)-β-D-xylopyranosyl (1→4)]-α-L-rhamnopyranosyl}-3-O-(α-L-rhamnopyranosyl)-4-O-(4'-methoxy-cinnamoyl)-β-D-fucopyranoside, presenegenin-(3)-β-D-glucopyranosido-(28)-2-O-[β-D-galactopyranosyl (1→4)-β-D-xylopyranosyl (1→4)-α-L-rhamnopyranosyl]-3-O-(α-L-rhamnopyranosyl)-4-O-(4'-methoxycinnamoyl)-β-D-fucopyranoside (=senegin III) and presenegenin- (3)-O-β-D-glucopyranosido-(28)-2-O-[β-D-galactopyranosyl (1→4)-β-D-xylopyranosyl (1→4)-α-L-rhamnopyranosyl]-4-O-(3', 4', 5'-trimethoxycinnamoyl)-β-D-fucopyranoside, respectively. The 13C nuclear magnetic resonance spectra of onjisaponins A, B, E and their derivatives were investigated and each carbon signal was assigned as shown in Table I.