title: Quantitation of 8-oxoguanine and strand breaks produced by four oxidizing agents.
abstract: Reactive oxygen species, produced endogenously or by exposure to environmental chemicals and ionizing radiation, induce a wide range of DNA lesions. The variety of chemistries associated with different oxidants suggests that each will produce a unique spectrum of DNA damage products. To extend our efforts to relate genotoxin chemistry to DNA damage, we measured both strand breaks and 8-oxoguanine (8-oxoG) in DNA after exposure to gamma-radiation, Fe(II)-EDTA/H2O2, Cu(II)/H2O2, and peroxynitrite at concentrations approaching physiological relevance. We found that the ratio of 8-oxoG to strand breaks varied more than 10-fold depending on the oxidizing agent: approximately 0.4 for Cu(II)/H2O2 and peroxynitrite and approximately 0.03 for Fe-(II)-EDTA/ H2O2 and gamma-radiation. In the case of Cu(II)/H2O2, the relative proportion of 8-oxoG and strand breaks was found to vary more than 2-fold (0.14-0.37) for different Cu(II) concentrations, consistent with other studies. We were able to detect 8-oxoG formation by peroxynitrite by using low peroxynitrite concentrations in conjunction with a sensitive immunoaffinity/HPLC-ECD methodology. The level of 8-oxoG relative to strand breaks produced by peroxynitrite was higher than that produced by Fe(II)-EDTA/H2O2 and gamma-radiation, which is consistent with the altered reactivity or accessibility of a non-hydroxyl radical species produced by peroxynitrite.
authors.affiliation: Department of Chemistry, Massachusetts Institute of Technology, Cambridge 02139-4307, USA.
authors.forename: L J
authors.initials: LJ
authors.lastname: Kennedy
authors.forename: K
authors.initials: K
authors.lastname: Moore
authors.forename: J L
authors.initials: JL
authors.lastname: Caulfield
authors.forename: S R
authors.initials: SR
authors.lastname: Tannenbaum
authors.forename: P C
authors.initials: PC
authors.lastname: Dedon
mesh_terms: D003300:Copper / Q000494:pharmacology; D004247:DNA / Q000187:drug effects* / Q000528:radiation effects; D018736:DNA Adducts / Q000737:chemistry; D004492:Edetic Acid / Q000494:pharmacology; D005296:Ferrous Compounds / Q000494:pharmacology; D005720:Gamma Rays; D006147:Guanine / Q000031:analogs & derivatives* / Q000032:analysis; D009566:Nitrates / Q000494:pharmacology; D016877:Oxidants / Q000494:pharmacology*; D018384:Oxidative Stress
chemical_list: D018736:DNA Adducts; D005296:Ferrous Compounds; D009566:Nitrates; D016877:Oxidants; C055526:Fe(II)-EDTA; C039642:peroxynitric acid; C024829:8-hydroxyguanine; D006147:Guanine; D003300:Copper; D004247:DNA; D004492:Edetic Acid