Rosmaric acid modulates the kinetics of DNA repair in human fibroblast cell line submitted to H2O2-induced genotoxic stress

Rosmarinic Acid (RA) is a natural phenolic compound found in Lamiaceae herbs and well known by its antioxidant and anti-inflammatory properties. RA has been also investigated as a chemopreventive agent; however, its ability to prevent or suppress DNA damage has not been investigated before in human cell lines. In the present study the effects of RA on DNA repair kinetics was investigated using the normal human fibroblast cell line (GM07492-A) submitted to in vitro genotoxic stress with H₂O₂. Cytotoxicity assay in a concentration range from 2–256µM was performed using the XTT method. Alkaline version of comet assay was employed to assess the DNA repair kinetics with 2, 4, 8µM of RA associated with hydrogen peroxide (H₂O₂) at 50µM. Cells were harvested immediately after DNA damage induction with H₂O₂ (T0), and 1h (T1), 2h (T2), 4h (T3) and 6h (T2) after recovery with RA. Results demonstrated that RA was not cytotoxic in all tested concentrations. Comet assay revealed that RA exhibits antigenotoxic activity by the improvement of the DNA repair kinetics in H₂O₂ treated cells. The reduction in the extension of DNA damage was not concentration dependent, but cells submitted RA treatment were completely recovered at T3. These results demonstrate that RA can protect DNA against oxidative injury, representing a potent chemoprotective agent in normal cells. The next step of this study includes the elucidation of the molecular signaling pathways involved in the DNA repair process modulated by RA treatment in conditions of genotoxic stress.