Objectives: To investigate whether the cytotoxic effect of Cimicifuga rhizoma extract is associated with cell death in the human keratinocyte (HaCaT) and human melanoma cell lines (G361). Methods: Apoptosis induced by Cimicifuga rhizoma extract was confirmed by water-soluble tetrazolium salts-1 (WST-1) assay, immunocytochemistry, and western blot. Additionally, the release of cytochrome c and apoptosis-inducing factor (AIF) was visualized by confocal laser scanning microscopy.Results: The results showed that Cimicifuga rhizoma extract significantly reduced the viability of G361 cells with half-maximal inhibitory concentration (IC 50) of 200 μg/ml, and the apoptotic process was found to occur via the activation of caspase-3 and caspase-9 pathways. Besides, the release of cytochrome c and AIF was also detected. Conclusions: This study suggests that Cimicifuga rhizoma extract causes apoptosis of human melanoma cells through the intrinsic apoptotic pathway.

Keywords: Apoptosis, Cimicifuga rhizoma, Melanoma