Cucurbitacin D isolated from Trichosanthes kirilowii induces apoptosis in human hepatocellular carcinoma cells in vitro

The aim of the present study is to examine the effects of the anti-tumor component isolated from Trichosanthes kirilowii on human hepatocellular carcinoma cells. Using Sephadex G-25 column chromatography, Sep-Pak Plus C18 cartridge and high-performance liquid chromatography (HPLC), we isolated the active component from trichosanthes extract. By fast atom bombardment mass spectrometric analysis, the molecular mass of the active fraction was determined, the active components identified, and their mechanisms of action were analyzed by cell growth assay, cell cycle analysis, TUNEL staining and Western blot analysis. We found that the anti-tumor components isolated from the extract of trichosanthes (EOT) are cucurbitacin D and dihydrocucurbitacin D, and suggest that cucurbitacin D induces apoptosis through caspase-3 and phosphorylation of JNK in hepatocellular carcinoma cells. These results suggest that cucurbitacin D isolated from Trichosanthes kirilowii could be a valuable candidate for anti-tumor drug.