in vitro challenge using thymoquinone on hepatocellular carcinoma (hepg2) cell line

black seed (nigella sativa) is considered as a biological response modifier. thymoquinone (tq) is the bioactive and the most abundant constituent of the volatile oil of this seed which has been shown to possess anti-inflammatory, antioxidant and anti-neoplastic effects. in this study, the effect of tq on hepg2 cell line was investigated in an attempt to identify its potential mechanism of action. cell viability and proliferation were assessed in presence of different concentrations of tq, which revealed a remarkable inhibition of hepg2 cells by tq in a dose dependant manner. tq ability to induced apoptosis was determined by flowcytometry and colorimetric measurement of caspases 3 and 9. the apoptotic effect of tq was much more dramatic after 12 h treatment and the activity of caspases 3 and 9 was increased. also, flowcytometric analysis of cell cycle revealed an early g1/s arrest of cells, which is characteristic of apoptosis. it could be concluded that thymoquinone is a promising anti-cancer agent for hepatocellular carcinoma.