title: Free-radical reactions induced by OH-radical attack on cytosine-related compounds: a study by a method combining ESR, spin trapping and HPLC.
abstract: Free-radical reactions induced by OH-radical attack on cytosine-related compounds were investigated by a method combining ESR, spin trapping with 2-methyl-2-nitrosopropane and high-performance liquid chromatography (HPLC). Cytidine, 2'-deoxycytidine, cytidine 3'-monophosphate, cytidine 5'-monophosphate, 2'-deoxycytidine 5'-monophosphate and their derivatives, of which 5,6-protons at the base moiety were replaced by deuterons, and polycytidylic acid (poly(C] were employed as samples. OH radicals were generated by X-irradiating an N2O-saturated aqueous solution. Five spin adducts were separated by HPLC. Examination of them by ESR spectroscopy and UV photospectrometry showed that spin adducts assigned to C5 and C6 radicals due to OH addition to the 5,6 double-bond, a deaminated form of the spin adduct derived from a C5 radical due to the cyclization reaction between C5' of the sugar and C6 of the base, and a spin adduct assigned to the C4' radical due to H abstraction by OH radicals were produced. From these results the sites of OH-radical attack and the subsequent radical reactions in cytosine-related compounds were clarified.
authors.affiliation: Department of Radiation Biology, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
authors.forename: W
authors.initials: W
authors.lastname: Hiraoka
authors.forename: M
authors.initials: M
authors.lastname: Kuwabara
authors.forename: F
authors.initials: F
authors.lastname: Sato
authors.forename: A
authors.initials: A
authors.lastname: Matsuda
authors.forename: T
authors.initials: T
authors.lastname: Ueda
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002851:Chromatography, High Pressure Liquid; D003562:Cytidine; D003597:Cytosine Nucleotides; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D006878:Hydroxides; D017665:Hydroxyl Radical; D015394:Molecular Structure; D013113:Spin Labels
chemical_list: D003597:Cytosine Nucleotides; D005609:Free Radicals; D006878:Hydroxides; D013113:Spin Labels; D017665:Hydroxyl Radical; D003562:Cytidine