Triterpenoid constituents from the roots of Paeonia rockii ssp. rockii.

An investigation of a chloroform-soluble extract from the roots of Paeonia rockii ssp. rockii yielded three new noroleanane triterpenoids (1-3) together with 19 known compounds. Their structures were established by analysis of the spectroscopic data. The effects of this chloroform-soluble extract and its major constituents on cell proliferation and apoptosis of a panel of human cancer cell lines (melanoma M-14, colon cancer HT-29, breast cancer MCF-7) were evaluated by the MTT bioassay and propidium iodide staining, respectively, in comparison with normal human embryonic kidney cells (HEK-293). Two of the triterpenoids, betulinic acid (4) and oleanolic acid (5), and the crude extract were cytotoxic and induced apoptosis selectively in the M-14 melanoma cell line. This effect was reversed by the caspase-inhibitor z-VAD-fmk, suggesting that such action is mediated by caspase-3 activation.