Spin adduct formation from lipophilic EMPO-derived spin traps with various oxygen- and carbon-centered radicals

2005 ◽  
Vol 69 (2) ◽  
pp. 297-305 ◽  
Author(s):  
Klaus Stolze ◽  
Natascha Udilova ◽  
Thomas Rosenau ◽  
Andreas Hofinger ◽  
Hans Nohl
Keyword(s):  
Adduct Formation ◽  
Spin Adduct ◽  
Spin Traps

Spin trapping by use of nitrosodurene and its derivatives

1982 ◽  
Vol 60 (12) ◽  
pp. 1532-1541 ◽  
Author(s):  
Ryusei Konaka ◽  
Shigeru Terabe ◽  
Taiichi Mizuta ◽  
Shigeru Sakata
Keyword(s):  
Hydrogen Peroxide ◽  
Esr Spectra ◽  
Spin Trapping ◽  
Nitroso Compounds ◽  
Spin Adduct ◽  
Spin Traps ◽  
Spectral Pattern ◽  
Alkyl Radicals ◽  
Alkyl Hydroperoxides ◽  
Tert Butyl Hydroperoxide

In spin trapping the N-methyl-N-phenylaminomethyl radical with nitrosodurene, an esr spectmm exhibiting line width alternation was observed despite the normal spectral pattern found with the use of nitroso-tert-butane. Nitrosodurene derivatives, N-duryl nitrone and methyl N-duryl nitrone, have been revealed to be other excellent spin traps for the N-, 0-, and S-centered radicals. Spin adducts of these radicals, which can be independently prepared by spin trapping with nitrosodurene, are stable and can be easily discriminated by large differences in β-hydrogen splittings or characteristic patterns. Methyl N-duryl nitrone reacted with tert-butyl hydroperoxide to give a spin adduct which could be clearly distinguished in the esr spectra from the tert-butoxy adducts prepared independently from other sources. Accordingly, it seems to be the tert-butylperoxy adduct. Similarly, hydrogen peroxide gave a different spectrum from the hydroxy adducts. Alkyl hydroperoxides caused molecule-induced homolysis with the nitroso compounds to produce alkoxy adducts of the respective nitroso compounds. Some phenyl and duryl alkoxy nitroxides undergo decomposition to give alkyl radicals which were trapped by the nitroso compounds.

Free radical production during phenylhydrazine-induced hemolysis

1982 ◽  
Vol 60 (12) ◽  
pp. 1528-1531 ◽  
Author(s):  
H. A. O. Hill ◽  
P. J. Thornalley
Keyword(s):  
Spin Trap ◽  
Spin Adduct ◽  
Phenyl Radical ◽  
Erythrocyte Suspension ◽  
Phenyl Radicals ◽  
Spin Traps ◽  
Free Radical Production ◽  
Radical Trapping ◽  
Radical Production ◽  
Moderate Yield

The production of phenyl radicals during phenylhydrazine-induced hemolysis has been demonstrated by the use of the spin traps, DMPO, M4PO, and LINPyBN. The phenyl spin adducts of DMPO and M4PO were produced in moderate yield by an oxygenated 1% erythrocyte suspension. With the lipid soluble spin trap LINPyBN, a dramatic increase (400%) in the yield of phenyl spin adduct was observed despite little increase in the rate of phenyl radical trapping. The production of phenyl spin adducts was decreased when phenylhydrazine-4-sulphonic acid or carbonmonoxyhemoglobin-containing erythrocytes were used. These results suggest that the reaction of phenylhydrazine with oxyhemoglobin leads to the formation of phenyl radicals that are preferentially trapped in the erythrocyte membrane.

Use of spin traps to elucidate radical mechanisms of oxidations by hydroperoxides catalyzed by hemeproteins

1982 ◽  
Vol 60 (12) ◽  
pp. 1463-1473 ◽  
Author(s):  
Brenda Walker Griffin
Keyword(s):  
Membrane Lipids ◽  
Liver Microsomes ◽  
Cumene Hydroperoxide ◽  
Significant Inhibition ◽  
Nitroso Compounds ◽  
Spin Adduct ◽  
Methyl Radical ◽  
Radical Product ◽  
Spin Traps ◽  
Catalytic Function

The use of the spin traps nitrosobenzene and 2-methyl-2-nitrosopropane has established that metmyoglobin and liver microsomal cytochrome P-450 initiate a radical decomposition of cumene hydroperoxide. With metmyoglobin and the alkyl nitroso compound, the only radical product of cumene hydroperoxide trapped was the methyl radical formed by β scission of the cumyloxy radical. With both hemeprotein initiators, nitrosobenzene trapped only the cumyl radical, considered to be a decomposition product of the unstable spin adduct phenylcumyloxynitroxide. Support for this proposal includes: (1) previous spin trapping studies of the chemical decomposition of cumene hydroperoxide; and (2) significant inhibition by nitrosobenzene of the one-electron oxidation of aminopyrine and the autoxidation of unsaturated membrane lipids resulting from addition of the hydroperoxide to liver microsomes. Aminopyrine altered the epr signal amplitudes of the spin adducts produced with both nitroso compounds, indicative of oxidation of aminopyrine by the methyl radical and reduction of cumene hydroperoxide by the aminopyrine radical. The participation of hydroperoxide-derived radicals in the low peroxidatic activities of certain hemeproteins is quite distinct from the catalytic function of the true hemeprotein peroxidases, which bring about an efficient two-electron reduction of specific hydroperoxides.

Vascular NAD(P)H oxidase is distinct from the phagocytic enzyme and modulates vascular reactivity control

2001 ◽  
Vol 280 (2) ◽  
pp. H658-H667 ◽  
Author(s):  
Heraldo P. Souza ◽  
Francisco R. M. Laurindo ◽  
Roy C. Ziegelstein ◽  
Carlos O. Berlowitz ◽  
Jay L. Zweier
Keyword(s):  
Nadph Oxidase ◽  
Vascular Tone ◽  
Vascular Reactivity ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Adduct Formation ◽  
Spin Adduct ◽  
Ros Generation ◽  
Resonance Spectroscopy ◽  
Dependent Manner ◽  
Significant Difference

An NAD(P)H oxidase has been hypothesized to be the main source of reactive oxygen species (ROS) in vessels; however, questions remain about its function and similarity with the neutrophil oxidase. Therefore, vascular superoxide generation was measured by electron paramagnetic resonance spectroscopy using the spin-trap 5,5′-dimethly-pyrroline- N-oxide in aortas from wild-type (WT) and gp91phox-deficient mice (gp91phox−/−), which do not have a functioning neutrophil NADPH oxidase. There was no significant difference between radical adduct formation by WT or gp91phox−/− mouse aortas either at baseline or after stimulation with NADPH or NADH. Also, spin-adduct formation was identical in the 100,000- g pellets obtained from WT and gp91phox−/− mouse aortas. SOD mimetics and the flavoenzyme inhibitor diphenyleneiodonium blocked spin-adduct formation from both intact vessels and particulate fractions. Other pharmacological inhibitors of metabolic pathways involved in ROS generation had no effect on this phenomenon. To examine the role of this enzyme in vascular tone control, aortic rings were suspended in organ chambers and preconstricted with phenylephrine to reach half-maximal contraction. Exposure to NADPH elicited a 20% increase in vascular tone, which was decreased by SOD mimetics in a concentration-dependent manner, suggesting that superoxide was responsible for this phenomenon. NADH had no effect on vascular tone. Thus superoxide is generated in the vessel wall by an NAD(P)H-dependent oxidase, which modulates vascular contractile tone. This enzyme is structurally and genetically distinct from the neutrophil NADPH oxidase.

On the spin trapping of chlorine atoms. Competition from chloride ions

1991 ◽  
Vol 69 (7) ◽  
pp. 1131-1133 ◽  
Author(s):  
Detlef Rehorek ◽  
Edward G. Janzen ◽  
Yashige Kotake
Keyword(s):  
Key Words ◽  
Epr Spectroscopy ◽  
Spin Trapping ◽  
Adduct Formation ◽  
Chloride Ions ◽  
Spin Adduct ◽  
Phenyl Radicals ◽  
Chlorine Atoms ◽  
Tert Butyl ◽  
Epr Spin Trapping

Chlorine atoms generated by photolysis of hexachloroethane add to C-phenyl-N-tert-butyl nitrone (PBN) to form persistent spin adducts that are readily detectable by EPR spectroscopy. The presence of chloride ions reduces spin adduct formation competitively. Chlorine atoms also react with tetraphenylarsenium ions to liberate phenyl radicals by radical replacement. Key words: EPR, spin trapping, C-phenyl-N-tert-butyl nitrone, PBN, photolysis, chlorine atoms, tetraphenylarsenium ion, hexachloroethane.

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