Effect of Hypoxia on Thymoquinone-Induced Production of Reactive Oxygen Species and Programmed Death of Tumor Cells

Using methods of flow cytometry and fluorescence analysis, a comparative analysis was conducted on the mechanisms of the response of human cervical carcinoma cells to thymoquinone, the main component of black cumin oils (Nigella sativa), under hypoxia and normoxic conditions. It was found that thymoquinone induced the death of tumor cells under both standard conditions (5% CO, 20% O) and reduced oxygen content (5% CO, 1% O). This caused mitochondrial dysfunction and increased intracellular production of reactive oxygen species. However, under hypoxia, the number of apoptotic cells and intracellular level of reactive oxygen species were significantly lower compared to standard conditions. These results suggest that the increase in resistance of tumor cells during hypoxia may be due to an increase in intracellular antioxidant content.