Effect of Nigella sativa (N. sativa L.) and oxidative stress on the survival pattern of MCF-7 breast cancer cells.

N. Sativa L., an oriental spice, has long been used as a natural medicine for treatment of many acute as well as chronic conditions. It has been used in the treatment of diabetes, hypertension, and dermatological conditions. There has been very few studies on the effects of N. Sativa as cancer prevention/therapy. Our objective therefore, was to expose MCF-7 breast cancer cells to aqueous and alcohol extracts and in combination with H2O2 as an oxidative stressor. Measurement of cell survival under various concentrations and combinations was conducted using standard cell culture techniques, exposure protocols in 96 well plates and Fluoro-spectrosphotometry. Following cellular growth to 90% confluency, exposure to water (WE) and ethanol (AE) extracts of N. sativa and H2O2 was performed. Toxicity index (LC50) was calculated from percent survival using regression analysis. Results showed that the alcohol extract and its combinations were able to completely inactivate the MCF-7 cells (LC50 ranged from 377.16-573.79 in descending potency for H2O2 + AE, AE and Mix of WE and AE). H2O2 alone effectively inactivated MCF-7 cells (LC50 = 460.94). The least effective combinations in descending potency were WE + H2O2, WE + AE + H2O2, and WE (LC50 were 725.79, 765.94, and 940.5 respectively. Combinations other than AE + H2O2 showed possible interactions, which lead to reduction in their potency. In conclusion, N. Sativa alone or in combination with oxidative stress were found to be effective in vitro in inactivating MCF-7 breast cancer cells, unveiling opportunities for promising results in the field of prevention and treatment of cancer.