Separation of a new triterpenoid saponin together with six known ones from Clematis tangutica (Maxim.) Korsh and evaluation of their cytotoxic activities

A new triterpenoid saponin, 3-O-β-D-allopyranosyl (1→3)-α-L-rhamnopyranosyl (1→2)-α-L-arabinopyranosyl hederagenin 28-O-α-L-rhamnopyranosyl (1→4)-β-D-glucopyranosyl (1→6)-β-D-glucopyranosyl ester (IV), together with six known ones Hederacholichiside F (I), Tanguticoside B (II), Tauroside St-H₁ (III), Hederoside H₁ (V), Kalopanaxsaponin G (VI), Hederasaponin B (VII) were separated from Clematis tangutica (Maxim.) Korsh. Their cytotoxic activities were evaluated. Saponins IV (new compound) and I showed selective inhibitory activities against HGC-27 with IC₅₀ values of 20.17 and 66.18 μM. Saponin VII exhibited extensive inhibitory action against HGC-27, Hela and SK-OV-3 with IC₅₀ values of 16.47-71.36 μM. Saponin III showed selective inhibitory activity against SK-OV-3 with the IC₅₀ value of 48.70 μM. All isolated saponins were inactive (IC₅₀ >150 μM) to GES-1.