A Study on Thymoquinone: Antioxidant Capacity and Anticancer Activities in LoVo Colorectal Cancer Cells

Thymoquinone has antioxidant and anticancer effects. This study investigates the cytotoxic, genotoxic, and apoptotic effects of black seed and its active ingredient, thymoquinone on colorectal cancer cells. The antioxidant content of Black seed methanolic extracts (BSME) with different concentrations (50, 500 and 1000 μg/mL) were determined by the photometric methods. The reactive oxygen production (iROS) of BSME and thymoquinone on colorectal cancer cells (LoVo) and normal epithelial cells (CCD18Co) were analyzed by the fluorometric methods. A luminometric glutathione kit was employed to observe the changes in intracellular glutathione (GSH) levels. Cytotoxicity was determined by the ATP method, genotoxicity was determined by Comet Assay, and the apoptosis was identified by the Acridine Orange/Ethidium Bromide (AO/EB) double dye method. The cytotoxicity was increased by BSME and thymoquinone in LoVo cells in a dose-dependent manner (p<0.001). BSME and thymoquinone also increased iROS, and induced apoptosis and DNA damage (p<0.001). High doses of BSME and thymoquinone on cancer and healthy cells have cytotoxic, genotoxic and apoptotic effects with pro-oxidant effects. Colorectal cancer cells are more sensitive than healthy cells.