Non-enzymatic fast repair of DNA oxidative damage might also exist in cells.
Many studies have shown that in a chemical system natural polyphenols can rapidly repair DNA oxidative damage. In this paper we report that in a cellular system the non-enzymatic fast repair activities of two natural polyphenols might also exist. The viability of a Chinese hamster ovary cell line (AA8) highly expressing the XRCC1 gene (a DNA repairing protein) treated with H2O2 is significantly higher than that of a normal Chinese hamster ovary cell line (CHO). Following inhibition of the enzymatic repair system by different inhibitors--methoxyamine (MX), 3-aminobenzamide (3AB) or nicotinamide (NIC)--DNA oxidative damage by H2O2 increased 2-5-fold in both cell lines. However, when natural polyphenols--rosmarinic acid (RA) or verbascoside (VER)--were added, DNA oxidative damage was significantly reduced. This decrease of DNA oxidative damage by RA or VER is not due to their scavenging activity for reactive oxygen species (ROS) because cells suffered from heavy ROS throughout the whole experimental process. Therefore, the decrease of DNA damage might be due to their non-enzymatic fast repair mechanisms. Further investigation showed that H2O2 induced a drop in the mitochondrial membrane potential (MMP), and that RA and VER were able to attenuate the drop. Previous studies have shown that H2O2 initiates a chain of events in cells, involving mtDNA damage, a drop in MMP and loss of repair activity. These results, taken together with our present results, suggest that the non-enzymatic fast repair mechanism exists not only in chemical systems but also might exist in cells.
Zhang
Qi
Q
School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China.
Pan
Jing
J
Zhao
Chenyang
C
Wang
Yuan
Y
Jia
Zhongjian
Z
Zheng
Rongliang
R
D000818:Animals; D016466:CHO Cells; D002470:Cell Survival / Q000187:drug effects; D002934:Cinnamates / Q000737:chemistry / Q000494:pharmacology*; D006224:Cricetinae; D003412:Cricetulus; D004249:DNA Damage; D004260:DNA Repair; D045643:DNA Repair Enzymes / Q000037:antagonists & inhibitors; D004268:DNA-Binding Proteins / Q000378:metabolism; D053630:Depsides / Q000737:chemistry / Q000494:pharmacology*; D005960:Glucosides / Q000737:chemistry / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000633:toxicity; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D018384:Oxidative Stress; D010636:Phenols / Q000737:chemistry / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D000076105:X-ray Repair Cross Complementing Protein 1; D000097123:Rosmarinic Acid; D059808:Polyphenols
D002934:Cinnamates; D045643:DNA Repair Enzymes; D004268:DNA-Binding Proteins; D053630:Depsides; D005960:Glucosides; D006861:Hydrogen Peroxide; D010636:Phenols; D017382:Reactive Oxygen Species; D000076105:X-ray Repair Cross Complementing Protein 1; D000097123:Rosmarinic Acid; C058956:acteoside; D059808:Polyphenols