Sibiricasaponins A-E, five new triterpenoid saponins from the aerial parts of Polygala sibirica L.

Five new triterpenoid saponins, named as sibiricasaponins A-E (1-5), were isolated and identified from the aerial parts of Polygala sibirica L., together with nine known triterpenoid saponins (6-14). The chemical structures of the five new triterpenoid saponins (1-5) were elucidated as 3β,19α-dihydroxyurso-12-ene-23,28-dioic acid 3-O-β-d-glucuronopyranoside (1), pomolic acid 3-O-(3-O-sulfo)-α-l-arabinopyranoside (2), pomolic acid 3-O-(4-O-sulfo)-β-d-xylopyranoside (3), pomolic acid 3-O-(2-O-acetyl-3-O-sulfo)-α-l-arabinopyranoside (4), and 3-O-β-d-glucopyranosyl medicagenic acid 28-O-β-d-galactopyranosyl (1→4)-β-d-xylopyranosyl (1→4)-α-l-rhamnopyranosyl (1→2)-(4-O-acetyl)-[β-d-apiofuranosyl (1→3)]-β-d-fucopyranosyl ester (5), respectively, on the basis of spectroscopic data and physicochemical evidences. These isolated compounds (1-14) were evaluated for their anti-ischemic effects on oxygen/glucose deprivation (OGD) model in vitro, and only compound 7 showed a weak anti-ischemia effect, with EC(50) value of 46.7μM.