Mechanistic studies of the reactions of nitrone spin trap PBN with glutathiyl radical.
We performed mechanistic studies of the reaction of PBN with the physiologically relevant glutathiyl radical, GS*, formed upon oxidation of the intracellular antioxidant, glutathione, GSH. The scavenging rate constant of GS* by PBN has been measured directly by laser flash photolysis and indirectly by competitive EPR of the spin adduct of PBN and another spin trap, DMPO (5,5-dimethyl-1-pyrroline N-oxide), and was found to be 6.7 x 107 M(-1) s(-1). Reverse decomposition of the paramagnetic PBN-glutathiyl radical adduct to the nitrone and thiyl radical was observed for the first time. The rate constant for the reaction of the monomolecular decomposition of the radical adduct was found to be 1.7 s(-1). Diamagnetic, EPR-invisible products of PBN adduct degradation were studied by 1H NMR and 19F NMR using newly synthesized fluorine-substituted PBN.
Polovyanenko
Dmitriy N
DN
International Tomography Center SB RAS, Novosibirsk 630090, Russia.
Plyusnin
Victor F
VF
Reznikov
Vladimir A
VA
Khramtsov
Valery V
VV
Bagryanskaya
Elena G
EG
D000975:Antioxidants / Q000737:chemistry; D003497:Cyclic N-Oxides / Q000737:chemistry* / Q000528:radiation effects; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods; D016166:Free Radical Scavengers / Q000737:chemistry; D005978:Glutathione / Q000737:chemistry*; D007834:Lasers; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008280:Magnetics; D015394:Molecular Structure; D009589:Nitrogen Oxides / Q000737:chemistry*; D010084:Oxidation-Reduction; D010782:Photolysis; D026422:S-Nitrosoglutathione / Q000737:chemistry / Q000528:radiation effects; D013997:Time Factors
D000975:Antioxidants; D003497:Cyclic N-Oxides; D016166:Free Radical Scavengers; D009589:Nitrogen Oxides; C015388:nitrones; C029217:phenyl-N-tert-butylnitrone; D026422:S-Nitrosoglutathione; C017245:5,5-dimethyl-1-pyrroline-1-oxide; D005978:Glutathione