title: Novel products generated from 2'-deoxyguanosine by hypochlorous acid or a myeloperoxidase-H2O2-Cl- system: identification of diimino-imidazole and amino-imidazolone nucleosides.
abstract: Hypochlorous acid (HOCl), generated by myeloperoxidase from H2O2 and Cl-, plays an important role in host defense and inflammatory tissue injury. We report here the identification of products generated from 2'-deoxyguanosine (dGuo) with HOCl. When 1 mM dGuo and 1 mM HOCl were reacted at pH 7.4 and 37 degrees C for 15 min and the reaction was terminated with N-acetylcysteine (N-AcCys), two products were generated in addition to 8-chloro-2'-deoxyguanosine (8-Cl-dGuo). One was identified as an amino-imidazolone nucleoside (dIz), a previously reported product of dGuo with other oxidation systems. The other was identified as a novel diimino-imidazole nucleoside, 2,5-diimino-4-[(2-deoxy-beta-D-erythro-pentofuranosyl)amino]-2H,5H-imidazole (dDiz) by spectrometric measurements. The yields were 1.4% dDiz, 0.6% dIz and 2.4% 8-Cl-dGuo, with 61.5% unreacted dGuo. Precursors of dDiz and dIz containing a chlorine atom were found in the reaction solution in the absence of termination by N-AcCys. dDiz, dIz and 8-Cl-dGuo were also formed from the reaction of dGuo with myeloperoxidase in the presence of H2O2 and Cl- under mildly acidic conditions. These results imply that dDiz and dIz are generated from dGuo via chlorination by electrophilic attack of HOCl and subsequent dechlorination by N-AcCys. These products may play a role in cytotoxic and/or genotoxic effects of HOCl.
authors.affiliation: Unit of Endogenous Cancer Risk Factors, International Agency for Research on Cancer, 150 Cours Albert Thomas, F-69372 Lyon Cedex 08, France.
authors.forename: Toshinori
authors.initials: T
authors.lastname: Suzuki
authors.forename: Mitsuharu
authors.initials: M
authors.lastname: Masuda
authors.forename: Marlin D
authors.initials: MD
authors.lastname: Friesen
authors.forename: Bernard
authors.initials: B
authors.lastname: Fenet
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ohshima
mesh_terms: D002712:Chlorides / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000737:chemistry* / Q000378:metabolism*; D006207:Half-Life; D006861:Hydrogen Peroxide / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006997:Hypochlorous Acid / Q000378:metabolism*; D007093:Imidazoles / Q000378:metabolism*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D009538:Nicotine / Q000378:metabolism; D009195:Peroxidase / Q000378:metabolism*; D012965:Sodium Chloride / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D002712:Chlorides; D007093:Imidazoles; D012965:Sodium Chloride; D009538:Nicotine; D006997:Hypochlorous Acid; D006861:Hydrogen Peroxide; D009195:Peroxidase; D003849:Deoxyguanosine