Effect of Amentoflavone, a Phenolic Component From Biophytum sensitivum, on Cell Cycling and Apoptosis of B16F-10 Melanoma Cells

Flavanoids are polyphenolic compounds that are found in fruits and vegetables and have diverse, beneficial biochemical and antioxidant effects. The objective of this study was to assess the effect of amentoflavone, a biflavanoid isolated from Biophytum sensitivum, on cell cycling distribution and apoptosis in B16F-10 melanoma cells. Treatment of B16F-10 melanoma cells with amentoflavone (10 mu g/mL) increased cells in the sub-G0/G1 phase accompanied by a decrease in G0/G1 phase cells in a time-dependent manner. A terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay of amentoflavone-treated B16F-10 melanoma cells confirmed that the cells were undergoing apoptosis. Amentoflavone was found to significantly inhibit B16F-10 melanoma-induced solid tumor development in C57BL/6 mice. The increase in apoptotic cells in paraffin sections obtained from amentoflavone-treated animals indicates that the reduction may be mediated through induction of apoptosis. Murine cell cycle-regulating genes, such as p21 and p27, and apoptosis-regulating genes, such as Bax and caspase-9, were found to be upregulated, whereas cyclin D1 and Bid were downregulated in amentoflavone-treated cells. These results demonstrate that amentoflavone can induce apoptosis via inhibiting progression of cells from G0/G1 to S phase and regulating genes involved in cell cycle regulation and apoptotic intrinsic pathways.