title: Radical trapping properties of imidazolyl nitrones.
abstract: The ability of ten imidazolyl nitrones to directly scavenge free radicals (R(*)) generated in polar ((*)OH, O(*)(2)(-), SO(*)(3)(-) cysteinyl, (*)CH(3)) or in apolar (CH(3)-(*)CH-CH(3)) media has been studied. When oxygen or sulfur-centered radicals are generated in polar media, EPR spectra are not or weakly observed with simple spectral features. Strong line intensities and more complicated spectra are observed with the isopropyl radical generated in an apolar medium. Intermediate results are obtained with (*)CH(3) generated in a polar medium. EPR demonstrates the ability of these nitrones to trap radicals to the nitrone C(alpha) atom (alpha radical adduct) and to the imidazol C(5) atom (5-radical adduct). Beside the nucleophilic addition of the radical to the C(alpha) atom, the EPR studies suggest a two-step mechanism for the overall reaction of R(*) attacking the imidazol core. The two steps seem to occur very fast with the (*)OH radical obtained in a polar medium and slower with the isopropyl radical prepared in benzene. In conclusion, imidazolyl nitrones present a high capacity to trap and stabilize carbon-centered radicals.
authors.affiliation: Laboratoire Pharmacochimie des Substances Naturelles et Pharmacophores Redox, Faculté des Sciences Pharmaceutiques, UMR 152 IRD-Université Paul Sabatier Toulouse III, 31062 Toulouse Cedex 9, France.
authors.forename: Karine
authors.initials: K
authors.lastname: Reybier
authors.forename: Jeremie
authors.initials: J
authors.lastname: Boyer
authors.forename: Vincent
authors.initials: V
authors.lastname: Farines
authors.forename: Fabrice
authors.initials: F
authors.lastname: Camus
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Souchard
authors.forename: Marie-Carmen
authors.initials: MC
authors.lastname: Monje
authors.forename: Vania
authors.initials: V
authors.lastname: Bernardes-Genisson
authors.forename: Solo
authors.initials: S
authors.lastname: Goldstein
authors.forename: Francoise
authors.initials: F
authors.lastname: Nepveu
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry*; D007501:Iron / Q000737:chemistry; D009589:Nitrogen Oxides / Q000737:chemistry*; D018384:Oxidative Stress; D013113:Spin Labels; D013329:Structure-Activity Relationship
chemical_list: C045076:Fenton's reagent; D016166:Free Radical Scavengers; D005609:Free Radicals; D007093:Imidazoles; D009589:Nitrogen Oxides; D013113:Spin Labels; C015388:nitrones; D006861:Hydrogen Peroxide; D007501:Iron