And spin trapping

Rosentel IK, Mosobba MM, Riesz P (1981) Sonolysis of perhalomethane as studied by EPR and spin trapping. J Magn Reson 45 359-361... 

Superoxide generation was detected via the NADPH-dependent SOD-inhibitable epinephrine oxidation and spin trapping [15,16], Grover and Piette [17] proposed that superoxide is produced equally by both FAD and FMN of cytochrome P-450 reductase. However, from comparison of the reduction potentials of FAD (-328 mV) and FMN (190 mV) one might expect FAD to be the most efficient superoxide producer. Recently, the importance of the microsomal cytochrome h558 reductase-catalyzed superoxide production has been shown in bovine cardiac myocytes [18]. 

In earlier studies the in vitro transition metal-catalyzed oxidation of proteins and the interaction of proteins with free radicals have been studied. In 1983, Levine [1] showed that the oxidative inactivation of enzymes and the oxidative modification of proteins resulted in the formation of protein carbonyl derivatives. These derivatives easily react with dinitrophenyl-hydrazine (DNPH) to form protein hydrazones, which were used for the detection of protein carbonyl content. Using this method and spin-trapping with PBN, it has been demonstrated [2,3] that protein oxidation and inactivation of glutamine synthetase (a key enzyme in the regulation of amino acid metabolism and the brain L-glutamate and y-aminobutyric acid levels) were sharply enhanced during ischemia- and reperfusion-induced injury in gerbil brain. 

Oubrahim, H., Richard, J.M., Cantin-Esnault, D. (1998). Peroxidase-mediated oxidation, a possible pathway for activation of the fungal nephrotoxin orellanine and related compounds. ESR and spin-trapping studies, Free Radic. Res., 28, 497-505. 

A number of reports on the thermal decomposition of peroxides have been published. The thermal decompositions of f-butyl peroxyacetate and f-butyl peroxypivalate, of HCOH and a kinetic study of the acid-induced decomposition of di-f-butyl peroxide in n-heptane at high temperatures and pressures have been reported. Thermolysis of substituted f-butyl (2-phenylprop-2-yl) peroxides gave acetophenone as the major product, formed via fragmentation of intermediate alkoxy radicals RCH2C(Ph)(Me)0. A study of the thermolysis mechanism of di-f-butyl and di-f-amyl peroxide by ESR and spin-trapping techniques has been reported. The di-f-amyloxy radical has been trapped for the first time. jS-Scission reaction is much faster in di-f-amyloxyl radicals than in r-butoxyl radicals. The radicals derived from di-f-butyl peroxide are more reactive towards hydrogen abstraction from toluene than those derived from di-f-amyl peroxide. 

The aim of this section is to give a concise description of the use of traps, to note the most popular traps, and mainly to underline the possible artifacts connected with the application of traps to ion radical reactions. The problem of radical trapping is also relevant because radicals are often the primary products of ion radical transformations. The radicals are, as a rule, not stable, and special traps—radical and spin traps—arc used to reveal them. 

Combined EPR and spin-trapping studies showed that solvent vapor and ambient gases (e.g., air) decompose to atoms or free radicals in the gaseous bubble interior. Water vapor is thermally dissociated into OH radicals, H atoms, and O atoms. The latter interconvert with OH radicals at the high pressures in the cavity and recombine in the cooler interfacial region to form Oz and H2Oz. The power dependence in the sonolytic transformation of a phenolic aqueous solution was found to be the first order. 

Koster R, Asmus K-D (1971) Die Reaktionen chlorierter Athylene mit hydratisierten Elektronen und OH-Radikalen in wassriger Losung. Z Naturforsch 26b 1108—1116 Krishna CM, Decarroz C, Wagner JR, Cadet J, RieszP (1987) Menadione sensitized photooxidation of nucleic acid and protein constituents. An ESR and spin-trapping study. Photochem Photobiol 46 175-182... 

Mossoba MM, Rosenthal I, Riesz P (1981) ESR and spin-trapping studies of dihydropyrimidines, y-Radiolysis in the polycrystalline state and UV photolysis in aqueous solution. Int J Radiat Biol 40 541-552... 

Niehaus H, Hildenbrand K (2000) Continuous-flow and spin-trapping EPR studies on the reactions of cytidine induced by the sulfate radical-anion in aqueous solution. Evidence for an intermediate radical cation. J Chem Soc Perkin Trans 2 947-952 Niles JC, Burney S, Singh SP, Wishnok JS, Tannenbaum SR (1999) Peroxynitrie reaction products of 3, 5 -di-0-acetyl-8-oxo-7,8-dihydro-2 -deoxyguanosine. Proc Natl Acad Sci USA 96 11729-11734... 

Zhang Z-Y, Kuwabara M, Yoshii G (1983) ESR and spin-trapping study of room-temperature radicals in y-irradiated polycrystalline pyrimidine nucleotides. Radiat Res 93 213-231... 

Irradiation of phenyliodonium salts lead to the formation of phenyl radicals. In the presence of C60 these radicals are efficiently trapped under formation of pheny-lated C6o derivatives, mainly the monoadduct. In reaction mixtures of C6o, phenyliodonium salts and spin traps like nitroso-tert-butane ( BuNO) or nitroso-durene (ND) no phenyl adducts with the spin traps could be observed after irradiation. This suggests that C6o is a more efficient scavenger for phenyl radicals than the spin traps [177], Other investigations yielded similar results, e.g., the photolysis of organomercury compounds in the presence of fullerenes leads to fullerene-derived radical adducts. These radical adducts can combine to form dimers that are thermally stable and accumulate in the samples [Eq. (7)] [178],... 

Pyridines, Amines, and Phosphines. We have not observed an ESR signal during the autoreduction with the above substrates. With the pyridines and phosphines so far investigated, the reduction probably has been too slow to generate appreciable concentrations of radical species. The autoreduction is much faster with primary and secondary amines, however the radicals produced are most likely too short-lived to detect with our present methods. We are investigating the applicability of rapid flow and spin trapping techniques. 

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