Protection against radiation-induced oxidative damage by an ethanolic extract of Nigella sativa L.

Abstract

Purpose: An ethanolic extract of Nigella sativa L. (EE-NS) was investigated for its antioxidant properties and radioprotective effects against γ-radiation-induced oxidative damage.

Materials and methods: The radical scavenging activity of the extract was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH), deoxyribose degradation and plasmid relaxation assays in a cell-free system. DNA damage studies were performed using a single cell gel electrophoresis (SCGE) assay and micronuclei (MN) formation. Moreover, the alterations in lipid peroxidation and antioxidant enzymes were measured by biochemical methods.

Results: EE-NS showed significant free radical scavenging and protection against DNA damage in cell free systems. Ex vivo treatment of mouse splenic lymphocytes with an ethanolic extract of N. sativa 1 h prior to irradiation (2 Gy) showed significant prevention of the formation of lipid-peroxides and intracellular reactive oxygen species (ROS), which correlated with radiation-induced apoptosis. Moreover, radiation-induced DNA damage was significantly prevented in splenocytes pre-treated with EE-NS. Swiss albino mice fed orally with the different doses of EE-NS (0–100 mg/kg bw) for five consecutive days followed by 2 Gy whole body irradiation (WBI) showed significant protection against oxidative injury to spleen and liver as measured by lipid peroxidation and the activity of antioxidant enzymes. These results were correlated with the prevention of DNA damage as measured by bone marrow micronuclei assay. Our results suggest that oral feeding of extract resulted in increased survival in mice exposed to WBI (7.5 Gy).

Conclusion: The results obtained from the different experimental systems suggest the radioprotective ability of EE-NS involving prevention of radiation-induced oxidative damage.

Keywords:

• Nigella sativa L.
• radioprotection
• free radicals
• oxidative stress
• antioxidant enzymes
• splenic lymphocytes

Acknowledgements

The authors sincerely thank Dr Amit Kumar, Shri Shailesh Sonar and Shri Binoj Kutty for reading and providing suggestions in finalisation of the manuscript. We thank Smt. Hansa D. Yadav, Shri Manjoor Ali and Shri L. V. Chaudhary for their technical assistance during animal experiments. We also acknowledge the facility provided by Department of Pathology, Bombay Veterinary College, Parel, Mumbai, for hematological analysis.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.