Cytotoxic triterpene saponins fromClematis mandshurica

Two new triterpene saponins, mandshunosides A and B (1 and 2), were isolated from the roots and rhizomes of Clematis mandshurica. Their structures were elucidated on the basis of spectroscopic evidence and hydrolysis products. Compounds 1 and 2 showed inhibitory activities against two colorectal human cancer cells HCT 116 (IC₅₀ 2.1 μM for 1 and 2.5 μM for 2) and HT-29 (IC₅₀ 3.7 μM for 1 and 3.3 μM for 2).