Chung-Ang University, Republic of Korea
Although several studies covered the anti-proliferative and cytotoxic effects of the rhizome extracts of Kaempferia parviflora Wall. ex. Baker towards cancer cells, cytotoxicity of its pure methoxyflavone components remain undetermined. This study was aimed to evaluate the cytotoxicity of 3,5,7,4´-tetramethoxyflavone (TeMF), 5,7,4´-trimethoxyflavone (TMF), and 5-hydroxy-3,7,3´,4´-tetramethoxyflavone (5-H-TeMF) purified from its rhizome extracts on human colorectal carcinoma (HCT- 15) cells. All these three compounds showed a dose-dependent inhibitory effect on HCT- 15 cells. Significant numbers of apoptotic nuclei and quantities of condensed chromatin were also observed. TMF produced a higher level of fragmented DNA compared to TeMF or 5-H-TeMF. In addition TMF-treated cells showed the highest levels of caspase-3 activity than those treated with the other two compounds. Caspase-3 activity was reduced when Z-VAD-FMK, a caspase inhibitor, was administered along with each compound. Furthermore, caspase-3 activity was increased by the four concentrations of TMF in a dose-dependent manner. These results strongly suggest that TeMF, TMF, and 5-H-TeMF caused cell death via an apoptotic pathway. Therefore all these compounds have the potentiality to be the novel anti-cancer drugs.