New cytotoxic triterpenoid saponins from the whole plant of Clematis lasiandra Maxim.

Four new oleanane type triterpenoid saponins (1-4) and three known saponins (5-7) were isolated from the whole plant of Clematis lasiandra Maxim. The structures of the four new compounds were elucidated as 3-O-β-D-ribopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-[β-D-glucopyranosyl-(1 → 4)]-β-D-xylopyranosyl hederagenin (1), 3-O-β-D-ribopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1→2)-β-D-xylopyranosyl oleanolic acid 28-O-β-D-glucopyranosyl ester (2), 3-O-β-D-ribopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-β-D-xylopyranosyl hederagenin (3) and 3-O-β-D-ribopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-[β-D-glucopyranosyl-(1→4)]-α-L-arabinopyranosyl hederagenin (4) on the basis of extensive spectroscopic analysis and chemical evidence. Compounds 1-7 were evaluated for their cytotoxicity against human tumor cell lines HL-60, Hep-G2 and SGC-7901, and all of the evaluated saponins showed significant cytotoxicity to those three tumor cell lines with IC₅₀ in the range from 1.40 to 19.50 μmol/L except for compounds 2 and 6.