Investigation of the anticarcinogenic effects of combined application of thymoquinone and carvacrol in cervical cancer cells

Cervical cancer is a significant public health concern, particularly in low- and middle-income countries. Due to the limitations of conventional treatments, alternative approaches based on natural compounds have gained increasing importance. This study investigated the individual and combined effects of thymoquinone derived from Nigella sativa and carvacrol obtained from Origanum species on HeLa cervical cancer cells. The human embryonic kidney cell line 293T was used as the control group. In the experimental groups, cell viability and cytotoxicity were evaluated using the MTT assay, cell migration was assessed with the scratch assay, and apoptotic effects were analyzed by immunocytochemical Bax/Bcl-2 staining. Statistical analyses were performed using GraphPad Prism 8. Thymoquinone exhibited cytotoxic effects on both HeLa and 293T cells at concentrations of 125 µM and above, and high doses were found to reduce cell migration. Although carvacrol was not directly applied to the cells, a marked decrease in cell viability was observed in wells adjacent to carvacrol-treated wells, which became more pronounced at higher doses (p<0.05). A similar effect was observed in the combined thymoquinone–carvacrol treatment. Both vapor-phase carvacrol and the combined application of thymoquinone and carvacrol were found to reduce migration in HeLa cells compared with controls. Immunocytochemical scoring demonstrated that vapor-phase carvacrol significantly increased the Bax/Bcl-2 ratio in HeLa cells compared with the control group (p<0.0001). Overall, the present findings indicate that both thymoquinone and carvacrol, individually or in combination, hold promise as potential therapeutic agents for cervical cancer. However, the anticancer effects of vapor-phase carvacrol identified in this study warrant further detailed investigation.