Effects of Nigella sativa aqueous extract on oxidative DNA damage

The black cumin (Nigella sativa) is claimed to have beneficial properties for human health, such as anti-bacterial, anti-carsinogenic, anti-inflammatory and antioxidant activities. The antioxidant effects of the black cumin may be partly explained by protection of cell components against free radicals. We evaluated the effect of aqueous black cumin extract for its potential protecting agent against oxidative damage to DNA in mononucleer leukocytes. Cells were pre-treated with various concentrations (100, 50, 25, 12,5, 6,25, 3,125 µg/mL) of the extract for 30 min-60 min at 37°C. Cells were then exposed to 10 and 50 mM of H2O2 for 5 min as an induction of oxidative stress. Evaluation of oxidative damage was performed using alkaline single-cell gel electrophoresis (Comet assay) for DNA fragmentation. Pre-treatments with black cumin extract reduced DNA damage at the concentrations of 100-25 µg/mL. Thus, black cumin showed cellular protection against endogenous DNA damage produced by H2O2.