Failure of carboxymethylglucan to inhibit oxidative DNA damage induced by hydroxyl radicals or singlet oxygen.
The ability of carboxymethylglucan (CMG), a high molecular water-soluble derivative of glucan, was evaluated to act as a scavenger of reactive oxygen species. Hydrogen peroxide and methylene blue plus visible light, well-defined oxidant factors, were used as a model agents for induction ofoxidative DNA damage in CaCo-2 cells. Both hydrogen peroxide and visible light gave rise to dose-dependent increase of DNA damage mediated by hydroxyl radicals (*OH) or singlet oxygen (1O2), respectively. While DNA lesions generated by hydrogen peroxide dominated by strand breakage, exposure of CaCo-2 cells to visible light led mainly to base modifications sensitive to formamidopyrimidine DNA-glycosylase (Fpg). Neither CMG nor ascorbic acid, a known antioxidant, induced any DNA damage in CaCo-2 cells. Pretreatment of cells with ascorbic acid prior to H2O2 or visible light exposure resulted into statistically significant reduction of DNA lesions induced by particular agent. However, pretreatment of CaCo-2 cells with CMG in concentration range from 0.01 microM to 1 microM reduced neither the level of strand breaks induced by hydrogen peroxide nor the number of Fpg-sensitive base modifications generated by visible light.
Cancer Research Institute of Slovak Academy of Sciences, Bratislava, Slovak Republic. exongaba@savba.sk
A
A
Gábelová
M
M
Plesková
D000975:Antioxidants / Q000494:pharmacology; D001205:Ascorbic Acid / Q000494:pharmacology; D018938:Caco-2 Cells; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005936:Glucans / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D017665:Hydroxyl Radical / Q000378:metabolism*; D007700:Kinetics; D008027:Light; D008956:Models, Chemical; D018384:Oxidative Stress; D010100:Oxygen / Q000378:metabolism*; D017382:Reactive Oxygen Species; D013997:Time Factors; D047071:beta-Glucans
D000975:Antioxidants; D005936:Glucans; D017382:Reactive Oxygen Species; D047071:beta-Glucans; D017665:Hydroxyl Radical; C029933:carboxymethyl-beta-1,3-glucan; D006861:Hydrogen Peroxide; D001205:Ascorbic Acid; D010100:Oxygen