Radical trapping properties of imidazolyl nitrones.
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.
Reybier
Karine
K
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.
Boyer
Jeremie
J
Farines
Vincent
V
Camus
Fabrice
F
Souchard
Jean-Pierre
JP
Monje
Marie-Carmen
MC
Bernardes-Genisson
Vania
V
Goldstein
Solo
S
Nepveu
Francoise
F
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
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