Nrf2-regulated antioxidant response ameliorating ionizing radiation-induced damages explored through in vitro and molecular dynamics simulations

Abstract

This study aims to investigate the mechanism of natural antioxidant ferulic acid (FA) in reducing oxidative stress followed by its inhibitory effect on the Keap1-Nrf2 complex. FA was treated ex vivo with human blood for 30 min at 37 °C ± 1 °C and exposed to 1.5 Gy of γ- rays of ⁶⁰Co (0.789 Gy/min) and allowed for repair for an hour at 37 °C ± 1 °C. FA's free radical scavenging capacity was measured using 2,7-dichlorofluorescein diacetate assay and cytogenetic assays. Further, a possible mechanism of protein-ligand interaction between FA and Keap1-Nrf2 pathway protein as a cellular drug target was studied using docking and molecular dynamics simulation. The 1.5 Gy of γ- rays exposed to pre-treated blood with FA showed a significant (p < 0.05) reduction in reactive oxygen species and DNA damage compared to the normal control blood group sample. The ligand-protein transient binding interaction in molecular dynamic simulation over a period of 100 ns was consistent and stable emphasizing complementary charge between the protein and ligand, speculating higher hydrophobic amino acid residues in the Keap1 active pocket. This might sway the Keap1 from interaction with Nrf2, and could lead to nuclear translocation of Nrf2 during radiation-induced oxidative stress. The present study emphasizes the radioprotective effect of FA against 1.5 Gy of γ- rays exposed to human blood and the application of in silico approaches helpful for the possible protective effect of FA.

Communicated by Ramaswamy H. Sarma

Keywords:

• Ferulic acid
• Oxidative stress
• DCFDA
• Cytogenetics
• Molecular docking
• MD simulations

Acknowledgements

Technical help from Ms Namita Kalra in sample acquisition in flow cytometry. We thank Dr. Manjunatha H, Professor, Department of Biochemistry, Bangalore University, India, for assisting in language editing.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All the data we generated in this paper is available in the body of the manuscript as supporting figures and tables. We do not have any ethical or legal consideration for not to make our data publicly available.

Additional information

Funding

The work was supported by Defence Research and Development Organisation, Government of India (NBC 1.29).