Structure elucidation of new acacic acid-type saponins from Albizia coriaria.

ABSTRACT

Three new acacic acid derivatives, named coriariosides C, D, and E (1-3) were isolated from the roots of Albizia coriaria. Their structures were elucidated on the basis of extensive 1D- and 2D-NMR studies and mass spectrometry as 3-O-[ß-D-xylopyranosyl-(1 → 2)-ß-D-fucopyranosyl-(1 → 6)-2-(acetamido)-2-deoxy-ß-D-glucopyranosyl]-21-O-{(2E,6S)-6-O-{4-O-[(2E,6S)-2,6-dimethyl- 6-O-(ß-D-quinovopyranosyl)octa-2,7-dienoyl]-4-O-[(2E,6S)-2,6-dimethyl-6-O-(ß-D-quinovopyranosyl)octa-2,7-dienoyl]-ß-D-quinovopyranosyl}-2,6-dimethylocta-2,7-dienoyl}acacic acid 28-O-ß-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 2)-ß-D-glucopyranosyl ester (1), 3-O-{ß-D-fucopyranosyl-(1 → 6)-[ß-D-glucopyranosyl-(1 → 2)]-ß-D-glucopyranosyl}-21-O-{(2E,6S)-6-O-{4-O-[(2E,6S)-2,6-dimethyl-6-O-(ß-D-quinovopyranosyl)octa-2,7-dienoyl]-4-O-[(2E,6S)-2,6-dimethyl-6-O-(ß-D-quinovopyranosyl)octa-2,7-dienoyl]-ß-D-quinovopyranosyl}-2,6-dimethylocta-2,7-dienoyl}acacic acid 28-O-α-L-rhamno pyranosyl-(1 → 2)-ß-D-glucopyranosyl ester (2), and 3-O-[ß-D-fucopyranosyl-(1 → 6)-ß-D-glucopyranosyl]-21-O-{(2E,6S)-6-O-{4-O-[(2E,6S)-2,6-dimethyl-6-O-(ß-D-quinovopyranosyl)octa-2,7-dienoyl)-ß-D-quinovopyranosyl]octa-2,7-dienoyl}acacic acid 28-O-ß-D-glucopyranosyl ester (3).