Radicals spin trapping

Asahi M, Asahi K, Wang X, Lo EH. Reduction of tissue plasminogen activator-induced hemorrhage and brain injury by free radical spin trapping after embolic focal cerebral ischemia in rats. J Cereb Blood Flow Metab 2000 20 452 57. 

Organic nitroxides (136a, 5), nitroparafins, and nitrolic acids (107) react with aqueous solutions of pentacyanocobaltate(II) salts to give alkyl pentacyanocobalt(III) nitroxide anion radicals, spin traps involving the formation of an N—Co bond (5). 

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. 

Brezova V, Stasko A, Biskupic S, Blazkova A, Havlinova B. Kinetics of hydroxyl radical spin trapping in photoactivated homogeneous (H202) and heterogeneous (Ti02, 02) aqueous systems. J Phys Chem 1994 98 8977-8983. 

Fig. 1. Two-compartment model to describe the metabolism of oxygen-derived free radicals in myocardial tissue. This figure depicts the progressive reduction of intracellular oxygen during the cycle of ischemia and reperfusion. Inhibitors of radical metabolism are shown in dashed boxes. Radical spin traps are shown in closed boxes.

In spite of the increased activities of SOD-1 and GPx and normal catalase activity, increased lipid peroxides in the blood plasma of DS patients have been reported (K10), as has as an increased accumulation rate of age pigments (i.e., lipofuscin and ceroid, known products of lipid peroxidation) (K9). In addition, an early study showed increased lipid peroxides in the cerebral cortex of DS fetal brains (B15). More recently, cortical neurons from fetal DS and age-matched normal brains were shown to differentiate normally early in cell cultures. However, DS neurons subsequently degenerated and underwent apoptosis, whereas the normal cells remained viable (B18). In addition, the DS neurons exhibited a three- to fourfold increase in reactive oxygen species and increased lipid peroxidation that preceded cell death. Importantly, DS neuron degeneration could be prevented by treatment with the free radical spin trap A-ferf-butyl-2-sulphophenylnitrone, the... 

In 2006, Rolando et al. (27A99) developed a new methodology based on liqnid chromatography (LC), mass spectrometry (LC-MS and LC-MS/MS) for the identification and qnantihcation of free-radical-spin-trap adducts. The improved method involved the use of a nano-LC fitted with a 75-pmcolumn for separation that allowed for shorter analysis time and higher sensitivity. The main advantage of... 

Menzel, E.R., W.R. Vincent, and J.R. Wasson Dipolar broadening of electron spin resonance lines of free radicals Spin-trapping studies of free radicals in cigarette smoke J. Magnetic Res. 21 (1976) 321-330. 

Peptide enzyme toxicity is related to free radical spin trap reactivity. Neuroreport 6 489-492 Hirano K, Hotta Y, Fujiki K, Kanai A (2000) Corneal amyloidosis caused by Leu518Pro mutation of betaig-h3 gene. Br J Ophthalmol 84 583-585... 

Although radicals may be measured directly in certain solid foods of low water activity, such as milk powder, indirect methods are required in liquid foods, such as emulsions and beer, because the radicals are very short lived (several seconds for peroxyl radicals). In solid samples, the ESR signals are, however, difficult to identify because of line broadening. In liquid samples, the use of artificial traps is required to form stable adducts that can be readily detected by ESR by reacting covalently with unstable radicals. Spin traps are usually nitroso compounds (e.g. tert-nitrosobutane), or nitrones (e.g. a-phe-nyl-ferf-butyl nitrone). The applications of spin traps are limited, however, because their efficiencies vary widely with different radicals. 

Danilczuk M, Corns ED, Schlick S (2008) Eragmentation of fluorinated model compounds exposed to oxygen radicals spin trapping ESR experiments and implications for the behaviour of proton exchange membranes used in fuel cells. Euel Cells 8(6) 436-452... 

In preliminary EPR measurements with aqueous model solutions of fructose-alanine (Fru-Ala) heated to 80 °C for 2 hrs only a very small amount of radicals could be detected. In order to prolong the lifetime of the radicals, spin trapping with 5,5-dimethyl-l-pyrroline-fV-oxide (DMPO) was applied. By formation of adducts with DMPO the free radicals are stabilized because of delocalization of the free electron between the nitrogen and the oxygen atom. 

Free radical traps (also loiown as free radical scavengers or spin traps). React with unstable short lived free radicals to form a relatively stable free radical (normally through the addition of the radical to the trap to form a nitroxide radical). Spin traps are normally used in conjimction with EPR spectroscopy for the detection and identification of short-lived free radicals. The identity of the radical can be inferred from the EPR spectrum of the spin adduct... 

CYPMPO is a free radical spin trap with excellent trapping capabilities toward hydroxyl and superoxide radicals in biological and chemical systems [145],... 

Table 2 Second-order rate constants for radical spin trapping for the traps PBN and DMPO...

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