Superoxide dismutase spin trapping

MPTP decreases glutathione levels and increases the levels of reactive oxygen species and the degree of lipid peroxidation in mouse brain slices in vitro and increases the levels of reactive oxygen species in mouse brain in vivo. MPTP neurotoxicity in vitro is reduced by glutathione. In vitro studies have shown that MPP neurotoxicity can be reduced by vitamin E, vitamin C, coenzyme Q, and mannitol (but not by superoxide dismutase, catalase, allopurinol, or dimethyl sulfoxide). P-Carotene, vitamin C, and /V-acctylcystcine partially protect against the neurotoxic effects of MPTP in mice, as do nicotinamide, coenzyme Q, and the free-radical spin trap A-tert-butyl-a-(sulfophenyl) nitrone. 

These are just a few examples. Spin-traps are now very widely used in biological studies, and, in general, are very effective. Since many such studies are directed at detection of 02 and OH radicals, it has become normal practice to check that the 02 - radical adduct is not formed when superoxide dismutase is added, and that the OH radical adduct is not formed when catalase is added to remove H202, which... 

Another important flavoprotein reaction occurs during the stimulation of neutrophils, which leads to a flux of superoxide radicals via the reduction of oxygen by a membrane-bound flavoprotein. Spin-trapping experiments with DMPO [149,150] have confirmed that superoxide radicals are released into the medium. Both O2 and DH (formed by secondary reactions of Oj) have been spin-trapped in neutrophil systems. Spin-trapped radicals are not observed in the presence of superoxide dismutase. 

Yang 1981). Support for the theory of alkyl radical transfer was provided by Ortiz de Monellano et al. (1983) who used the electronic paramagnetic resonance spin-trapping technique to detect the 2-phenylethyl radical formed during microsomal biotransformation of phenelzine. Production of the a-(4-pyridyl 1 -oxide)-N-ferf-butylnitrone/2-phenyl-ethyl radical adduct was dependent on the presence of active microsomes, phenelzine, NADPH (or NADH), and spin trap a-(4-pyridyl l-oxide)-N-ferf-butylnitrone (Ortiz de Monellano et al. 1983). The addition of catalase and superoxide dismutase resulted in a 28.5 and 24 % decrease in radical production, respectively (Rumyantseva et al. 1991). The concentration of the a-(4-pyridyl l-oxide)-N-ferf-butylnitrone/2-phenylethyl radical adduct decreased significantly in the presence of metal chelators, i.e. EDTA, diethylenetriaminepentaacetic acid (DTPA), or deferoxamine mesylate. 

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