Direct detection of the cation radical of the spin trap α-phenyl-N-tert-butylnitrone

Zubarev, Valentin; Brede, O.

doi:10.1039/p29940001821

Cited by 30 publications

(28 citation statements)

References 57 publications

(4 reference statements)

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“…[15"28"29] The value of A T is in agreement with a PBN-derived radical with the structure similar to a spin trapped radical adduct, I, whereas it is too large to originate from a PBN radical cation, II, which could have been formed by a direct one-electron transfer oxidation of PBN. [28] a 50 G ~ …”

Section: Reaction Of Ferrylmyoglobin With Pbn During Freezingmentioning

confidence: 99%

Reduction of ferrylmyoglobin by the spin trapN-tert-butyl-α-phenylnitrone (PBN) in aqueous solution and during freezing

Kröger-Ohlsen

Andersen

Skibsted

2000

Free Radical Research

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The hypervalent muscle pigment ferrylmyoglobin, formed by activation of metmyoglobin by hydrogen peroxide, was found to be reduced in a second-order reaction by N-tert-butyl-alpha-phenylnitrone (PBN, often used as a spin trap). In acidic aqueous solution at ambient temperature, the reduction is relatively slow (deltaH++ = 65+/-2kJ x mol(-1) and deltaS++ = -54+/-7 J x mol(-1). K(-1) for pH = 5.6), but phase transitions during freezing of the buffered solutions accelerates the reaction between ferrylmyoglobin and PBN. In these heterogenous systems at low temperature (but not when ice-formation was inhibited by glycerol), a PBN-derived radical intermediate was detected by ESR-spectroscopy, identified as a nitroxyl radical by a parallel nitrogen hyperfine coupling constant of 31.8 G, and from microwave power saturation behavior concluded not to be located in the heme-cleft of the protein. The acceleration of the reaction is most likely caused by a lowering of the pH during the freezing of the buffered solutions whereby ferrylmyoglobin becomes more oxidizing.

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Section: Reaction Of Ferrylmyoglobin With Pbn During Freezingmentioning

confidence: 99%

Reduction of ferrylmyoglobin by the spin trapN-tert-butyl-α-phenylnitrone (PBN) in aqueous solution and during freezing

Kröger-Ohlsen

Andersen

Skibsted

2000

Free Radical Research

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“…eqn (43) where R 1 = MeO • [160,161]. The results are collated in Table 21 together with those for attack of phenyl radical upon some small alcohols [162] and of PhMeCHO • upon ethylbenzene [163].…”

Section: ·4mentioning

confidence: 99%

“…The key intermediate ST + • in reaction (23) has been characterised by pulse radiolysis, flash photolysis and low-temperature EPR spectroscopy [43] for ST=PBN with max 420 nm. The EPR spectrum of PBN +• after warning the matrix is that of an aminoxyl-type radical.…”

Section: ·4·2 Inverted Spin Trappingmentioning

confidence: 99%

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Kinetic Aspects of Spin Trapping

Kemp

1999

prog. rct. kin. mech.

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288 1. 3·2·4 Rate constants of dimerization 330 3·2·5 Induced decomposition of spin adducts 334 3·3 Rates of isomerization reactions from spin trapping 336 3·4 Rates of radical abstraction reactions 341 3·5 Rates of radical addition reactions 345 3·6 Rates of polymerisation processes 345 3·7 Rates of reactions of excited states 349 3·7·1 Rates of abstraction reactions by excited states 349 3·7·2 Interactions of excited states with spin adducts 350 3·8 Reaction rates of transient radicals with stable aminoxyls 350 3·9 Radical traps as mediators in electron-transfer reactions 352 4. ACKNOWLEDGEMENTS 353 REFERENCES 353ABSTRACT Kinetics are described of the spin-trapping process itself, based on indirect methods such as radical clocks and other competition methods, and also direct methods based on flash photolysis and pulse radiolysis. The stability of spin traps and their dimerization are discussed, as is the stability of spin adducts, once formed. Caution is given over the utilisation of spin traps in photo -and redox systems where the spin trap can undergo excitation and/or dissociation to lead to radicals which undergo trapping processes to give potentially misleading spectral data. The use of well-authenticated spin trapping kinetic data to examine rates of ringopening and -closing and isomerization reactions is covered. The role of spin trapping as a probe of biochemical processes is also included, with particular reference to the trapping of hydroxyl and superoxide radicals. GLOSSARYBPG alkyl tert-butyl peroxyglyoxalates DMPO 5,5-dimethyl-1-pyrroline-N-oxide DMSO dimethyl sulfoxide epr electron paramagnetic resonance HFCC hyperfine coupling constant MBN methylene-N-tert-butylnitrone MNP 2-methyl-2-nitrosopropane NB nitrosobenzene ND nitrosodurene NM nitromethane PBN phenyl tert-butyl nitrone PMNB pentamethylnitrosobenzene SOD superoxide dismutase TBNtri-tert-butylnitrosobenzene TEMPO 2,2,6,6-tetramethylpiperidine N-oxyl 1.

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“…(lb), (where "R is the SO 4" radical) to forro antioxidant radicals A'. In addition, SO 4" can oxidize spin trap DMPO to its cation DMPO +" [42]:…”

Section: Thermal Initiation Of Radical Formation From K2s208mentioning

confidence: 99%

Free radical scavenging activities of white and red wines: An EPR spin trapping study

et al. 2002

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Abstraet. Free radical scavenging activities of wine samples were investigated by means of electron paramagnetic resonance (EPR) spin trapping. 1,l-Diphenyl-2-picrylhydrazyl served as a source of free radicals, "OH radicals were produced by the Fenton system, and in situ thermally generated SO 2" radicals from K2S20 s and carbon-centered radicals from azo-compounds were also used. 5,5-Dimethylpyrroline-N-oxide (DMPO) was used as a spin trapping agent. Three white and four red wine samples from the Slovak wine regions, along with 12% (v/v) aqueous ethanol solution as a reference sample, were compared. In general, the !owest scavenger activity was found in the reference sample, a higher one in the white, anda considerab[y higher one in the red wines, except when the Fenton system was used as the radical source. Here, unexpectedly, unlike in the other radical sources, the wine samples increased the yield of DMPO-adducts by about 5 times, compared to the reference sample. This is probably due to ah additional activation of the Fenton system by wine components. Higher concentrations of Mn '+ ions as determined by EPR spectroscopy corresponded to an increased scavenging activity of wines.

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Direct detection of the cation radical of the spin trap α-phenyl-N-tert-butylnitrone

Cited by 30 publications

References 57 publications

Reduction of ferrylmyoglobin by the spin trapN-tert-butyl-α-phenylnitrone (PBN) in aqueous solution and during freezing

Reduction of ferrylmyoglobin by the spin trapN-tert-butyl-α-phenylnitrone (PBN) in aqueous solution and during freezing

Kinetic Aspects of Spin Trapping

Free radical scavenging activities of white and red wines: An EPR spin trapping study

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