OBJECTIVETo investigate the anti-cancer effects of crude extract from Melia toosendan Sieb. et Zucc and its possible molecular mechanisms in vitro and in vivo.

METHODSTransonic alcohol-chloroform extraction method was used to extract toosendanin from the bark of Melia toosendan Sieb. et Zucc, and the content of toosendanin in the crude extract was measured by high performance liquid chromatography (HPLC). Anti-cancer effects of crude extract from Melia toosendan Sieb. et Zucc were investigated in in vivo and in vitro studies. In the in vitro experiment, human hepatocellular carcinoma cell lines SMMC-7721 and Hep3B were co-incubated with toosendanin crude extract of different concentrations, respectively. In the in vivo experiment, BALB/c mice were subcutaneously inoculated with mouse hepatocellular carcinoma H22 cells and treated with crude extract.

RESULTSHPLC revealed the content of toosendanin was about 15%. Crude extract from Melia toosendan Sieb. et Zucc inhibited cancer cells growth in a dose- and time-dependent manner. The 50% inhibitory concentration (IC50, 72 h) was 0.6 mg/L for SMMC-7721 cells and 0.8 mg/L for Hep3B cells. Both high-dose [0.69 mg/(kg d)] and low-dose [0.138 mg/(kg d)] crude extract could markedly suppress cancer growth, and the inhibition rate was greater than 50%. Hematoxylin and eosin staining showed necrotic area in cancers and transmission electron microscopy displayed necrotic and apoptotic cancer cells with apoptotic bodies. Immunohistochemistry showed that the expression of Bax and Fas increased and the expression of Bcl-2 reduced.

CONCLUSIONSToosendanin extract has potent anti-cancer effects via suppressing proliferation and inducing apoptosis of cancer cells in vivo and in vitro. The mechanism of apoptosis involves in mitochondrial pathway and death receptor pathway.