Evaluation of Cytotoxic Effects and Selectivity of <i>Nigella sativa</i> Extracts on MCF-7 and HDF Cell Lines

Abstract

Background: Breast cancer, one of the most common and lethal cancers in women, faces multiple therapeutic challenges, including side effects and the lack of selectivity of conventional drugs. In this regard, Nigella sativa, due to its numerous bioactive compounds and proven therapeutic properties, has emerged as a promising candidate for cancer treatment. Objectives: This study aimed to investigate the anticancer effects and toxicity of aqueous and hydroalcoholic extracts of N. sativa on human breast cancer (MCF-7) cells and normal human dermal fibroblasts (HDF). Methods: Aqueous and hydroalcoholic extracts of N. sativa were prepared, and their compound profiles were determined using high-performance liquid chromatography (HPLC). Cytotoxicity was evaluated using the MTT assay across a concentration range of 6.25 to 6400 µg/mL after 24 hours of treatment. Statistical analysis was performed using ANOVA with a significance level of P < 0.05. Results: The results demonstrated that the effects of the extracts were dependent on their type, concentration, and the nature of the target cells. The aqueous extract significantly reduced the viability of HDF cells at concentrations of 100 µg/mL and above, while its significant anticancer effect on MCF-7 cells began only at 400 µg/mL and above. The hydroalcoholic extract exhibited a dual effect: At low concentrations (12.5 - 50 µg/mL), it increased the viability of normal cells, whereas at high concentrations, it decreased it. This extract also showed a dual effect on cancer cells, increasing their viability at very low concentrations (6.25 and 12.5 µg/mL) and significantly reducing it only at a high concentration (800 µg/mL) (P < 0.05). Conclusions: The findings indicate that although N. sativa extracts possess concentration-dependent anti-proliferative potential, they lack the desired therapeutic selectivity, as concentrations effective against cancer cells also impose significant toxicity on normal cells. These results underscore the pharmacological complexity of the response and highlight the need for future studies to optimize dosage and formulation for the safe and effective exploitation of this potential.