Cytotoxic Oleanane-Type Triterpenoid Saponins from the Rhizomes of Anemone rivularis var. flore-minore

Phytochemical investigation of the n-BuOH extract of the rhizomes of Anemone rivularis var. flore-minore led to the isolation of five new oleanane-type triterpenoid saponins 1–5, together with five known saponins 6–10. Their structures were determined by the extensive use of 1D and 2D NMR experiments, along with ESIMS analyses and acid hydrolysis. The aglycone of 4 and 5 was determined as 21α-hydroxyoleanolic acid, which was reported in this genus for the first time. The cytotoxicity of these compounds was evaluated against four human cancer cell line, including HL-60 (promyelocytic leukemia), HepG2 (hepatocellular carcinoma), A549 (lung carcinoma) and HeLa (cervical carcinoma). The monodesmosidic saponins 6–8 exhibited cytotoxic activity toward all tested cancer cell lines, with IC50 values in the 7.25–22.38 μM range