Novel triterpene saponins isolated from Clematis mandshurica and their inhibitory activities on NO production

Four new triterpene saponins, mandshunosides F-I ( 1-4 ), together with five known compounds ( 5-9 ), were isolated from the roots and rhizomes of Clematis mandshurica. Their structures were elucidated on the basis of spectroscopic evidences and hydrolysis products. Bisdesmosidic saponin ( 3-9 ) showed modest suppression of NO production with the inhibition ratios in the range of 51.3%-64.6% at 50 μmol·L^-1, whereas monodesmosidic saponins with a free carboxyl group at C-28 ( 1 and 2 ) showed potent inhibitory activities with IC₅₀ values being 12.7 and 8.3 μmol·L^-1, respectively.