Scavenging effect of N-acetyl-cysteine on H2O2-caused oxidative DNA damage

Objectives: Hydrogen peroxide (H2O2), which is frequently used as bleaching agent may cause severe DNA damage. Objective of this investigation was to analyze whether different concentrations of the ROS scavenger N-acetyl-cysteine (NAC) decrease DNA damage. Materials and Methods: PhiX-174 RF plasmid DNA was used to determine single and double strand breaks as parameter of DNA damage. NAC was added to plasmid DNA treated with 0.1 mM of H2O2 for 30 minutes. Plasmid DNA exposed to H2O2 and NAC was used as negative control. After treatment of plasmids, DNA was loaded into a 1% agarose gel. Following electrophoresis, gels stained with 0.5 µg/mL ethidium bromide were photographed under ultraviolet illumination and analyzed with NIH ImageJ software to analyze quality (single-/double-strand breaks) and quantity of DNA damage. Differences of results between groups were evaluated for statistical significance using Student's paired t-test (p< 0.05). Results: NAC significantly reduced oxidative DNA damage at concentrations of 0.5mM, 1mM, 2mM, and 5 mM. No scavenging effect was observed at a concentration of 0.1 mM NAC. Although, no linear DNA was observed at 10mM NAC, the concentration of open circular DNA was significantly higher compared to negative control (p < 0.05). Conclusions: Our data indicate that oxidative DNA damage can be reduced by NAC dependent on its concentration.