title: Total antioxidant capacity and nuclear DNA damage in keratinocytes after exposure to H2O2.
abstract: Studies of oxidative stress have classically been performed by analyzing specific, single antioxidants. In this study, susceptibility to oxidative stress in the human keratinocyte cell line NCTC2544 exposed to hydrogen peroxide (H2O2) was measured by the TOSC (total oxyradical scavenging capacity) assay, which discriminates between the antioxidant capacity toward peroxyl radicals and hydroxyl radical. The generation of H2O2-induced DNA damage, total antioxidant capacity and levels of antioxidant enzymes (catalase, superoxide dismutase, glutathione reductase, glutathione S-transferase, glutathione peroxidase) were studied. Exposure to H2O2-induced DNA damage that was gradually restored while a significant reduction in cellular TOSC values was obtained independently of stressor concentrations and the degree of DNA repair. Whereas TOSC values and cell resistance to H2O2 showed a good relationship, the extent of DNA damage is independent from cellular total antioxidant capacity. Indeed, maximum DNA damage and cell mortality were observed in the first 4 h, whereas TOSC remained persistently low until 48 h. Catalase levels were significantly lower in exposed cells after 24 and 48 h. Keratinocytes exposed after 48 h to a second H2O2 treatment exhibited massive cell death. A possible linkage was observed between TOSC values and NCTC2544 resistance to H2O2 challenge. The TOSC assay appears to be a useful tool for evaluating cellular resistance to oxidative stress.
authors.affiliation: Institute of Biology and Genetics, University of Perugia, Italy.
authors.forename: T
authors.initials: T
authors.lastname: Armeni
authors.forename: M
authors.initials: M
authors.lastname: Battino
authors.forename: A
authors.initials: A
authors.lastname: Stronati
authors.forename: A
authors.initials: A
authors.lastname: Pugnaloni
authors.forename: G
authors.initials: G
authors.lastname: Tomassini
authors.forename: G
authors.initials: G
authors.lastname: Rosi
authors.forename: G
authors.initials: G
authors.lastname: Biagini
authors.forename: G
authors.initials: G
authors.lastname: Principato
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D020552:Comet Assay; D004249:DNA Damage; D016166:Free Radical Scavengers / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000633:toxicity*; D017665:Hydroxyl Radical / Q000378:metabolism; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D008854:Microscopy, Electron; D018384:Oxidative Stress / Q000187:drug effects*; D010545:Peroxides / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D010545:Peroxides; D017382:Reactive Oxygen Species; C049375:perhydroxyl radical; D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide; D002374:Catalase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D005982:Glutathione Transferase