Trapping of Free Radicals formed by γ-Irradiation of Organic Compounds

Lagercrantz, Carl; Forshult, Stig

doi:10.1038/2181247a0

Cited by 82 publications

(27 citation statements)

References 8 publications

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“…The reactions of OH radicals were investigated by uv photolysis of aqueous solutions containing hydrogen peroxide and the amine or polyamine. The direct effects of ionizing radiation on the polyamines in the solid state were investigated by y-radiolysis of the polycrystalline solids followed by dissolution in a solution containing the spin-trap (22,23).…”

Section: Andh~-(ch~)-~~h~-(ch~)~-~~h~) Etc Asmentioning

confidence: 99%

Electron spin resonance of spin-trapped radicals of amines and polyamines. Hydroxyl radical reactions in aqueous solutions and γ-radiolysis in the solid state

Mossoba¹,

Rosenthal²,

Riesz³

1982

Can. J. Chem.

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MAGDI M. MOSSOBA, IONEL ROSENTHAL, and PETER RIESZ. Can. J. Chem. 60, 1493 (1982). The reactions of hydroxyl radicals with methylamine, dimethylamine, trimethylamine, diethylamine, see-butylamine, ethylenediamine, 1,3-diaminopropane, putrescine, cadaverine, 1,7-diaminoheptane, ornithine, spermidine, spermine, agmatine, and arcaine in aqueous solutions have been investigated by spin-trapping and esr. Hydroxyl radicals were generated by the uv photolysis of H,O, and 2-methyl-2-nitrosopropane (MNP) was used as the spin-trap. The effects of ionizing radiation on the same polyamines in the polycrystalline state were also investigated. The free radicals produced by y-radiolysis of these solids at ro0.m temperature in the absence of air were identified by dissolution in aqueous solutions of MNP. The predominant reaction of OH with amines and polyamines below pH 7 was the abstraction of hydrogen atoms from a carbon that is not adjacent to the protonated amino group. For agmatine and arcaine which contain guanidinium groups abstraction occurred from the a-CH. Dimethylamine was oxidized to the dimethylnitroxyl radical by H,O, in the dark. y-Radiolysis of polyamines in the polycrystalline state generated radicals due to H-abstraction from either the a-CH or from a carbon atom in the middle of the alkyl chain. The deamination radical was obtained from ornithine. Faisant appel B la rpe et B I'utilisation de piegeurs de spin, on a itudiC la reaction des radicaux hydroxyles avec des solutions aqueuses des amines suivantes: methylamine, dimethylamine, trimethylamine, diethylamine, see-butylamine, Cthylknediamine, I diamino-1,3 propane, putrescine, cadavtrine, diamino-1,7 heptane, ornithine, spermidine, spermine, agmatine et arcaine. Les

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Section: Andh~-(ch~)-~~h~-(ch~)~-~~h~) Etc Asmentioning

confidence: 99%

Electron spin resonance of spin-trapped radicals of amines and polyamines. Hydroxyl radical reactions in aqueous solutions and γ-radiolysis in the solid state

Mossoba¹,

Rosenthal²,

Riesz³

1982

Can. J. Chem.

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“…In the photolysis of alkyl nitrites, the formation of dialkyl nitroxides, detectable by EPR spectroscopy, is usually described as shown in Equations (5) and (6) [2,3] (Scheme 1), with the key step of the process being the formation of the nitrosoalkyl derivative [Eq. (5)], which depends on the concentration of both the alkyl radical and the free NO.…”

Section: Resultsmentioning

confidence: 99%

“…For the formation of the corresponding nitrosoalkyl derivative, or the hydroxamic acid in the synthesis of steroids, the key step commonly accepted is the encounter of the alkyl radical and NO. But, it is now well documented that alkyl nitrites can themselves act as efficient traps for alkyl radicals, [1][2][3] and thus a possible alternative and/or competitive mechanism accounting for the formation of the nitrosoalkyl derivatives is hypothesized.…”

Section: Introductionmentioning

confidence: 99%

The Barton Reaction: Can a More Tenable Pathway Be Hypothesized for the Formation of Nitrosoalkyl Derivatives?

Grossi

2005

Chemistry A European J

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Herein, we report that in the formation of nitrosoalkyl derivatives during the photolysis of alkyl nitrites, the formation of the intermediate alkyl alkoxy nitroxide, due to the trapping of alkyl radicals by the starting nitrite, is the key step of the entire process. In fact, these nitroxides, detectable by EPR spectroscopy, decay to the final nitroso derivatives under thermodynamic control. In light of this, the Barton reaction mechanism has been reviewed. The nitrosoalkyl derivatives, or the hydroxamic acids when steroids are involved, have now to be considered as the ending products of the entire process and not, unless a very high concentration of NO is present in the medium, the result of a direct reaction of NO with the alkyl radical, as is commonly accepted.

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“…It has been demonstrated previously that spin trapping with MNP can be applied to the study of the effect of ionizing radiation on polycrystalline solids (13)(14)(15)(16). The solids are y-irradiated and subsequently dissolved in aqueous MNP solutions.…”

Section: Introductionmentioning

confidence: 99%

Electron spin resonance of spin trapped radicals in γ-irradiated polycrystalline dipeptides. Chromatographic separation of radicals

Makino¹,

Riesz²

1982

Can. J. Chem.

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KEIsUKE MAKINO and PETER RIESZ. Can. J. Chem. 60, 1480Chem. 60, (1982. Polycrystalline dipeptides (glycyl-glycine, glycyl-L-valine, glycyl-L-leucine, L-alanyl-glycine, and L-prolyl-L-alanine) were y-irradiated at room temperature in the absence of air. Subsequently they were dissolved in aqueous solutions containing 2-methyl-2-nitrosopropane as the spin trap. From the esr spectra of the nitroxide radicals separated by high-performance liquid chromatography, structural assignments of the radicals were made. For glycyl peptides, H-abstraction from the a-carbon atoms of the carboxyl terminal residues and from the side-chains were observed. For L-alanyl-glycine, H-abstraction from the glycyl residue and the formation of the deamination radical could be shown to occur. For L-prolyl-L-alanine, the ring opening (deamination) reaction, decarboxylation and H-abstraction from the C-terminal a-carbon were seen. KEISUKE MAKINO et PETER RIESZ. Can. J. Chem. 60, 1480 (1982). On a irradie aux rayons y, a la temperature ambiante et en I'absence d'air, les dipeptides polycristallins suivants:On les a ensuite dissous dans des solutions aqueuses contenant le capteur de spin, methyl-2 nitroso-2 propane. A partir des spectres de rpe des radicaux nitroxydes, skpares par chromatographie en phase liquide a haute performance, on a pu determiner les structures des radicaux. On a observe, dans le cas des peptides glycidiques, I'klimination d'un hydrogene partir des atomes de carbone en a du residue terminal carbxyle e t a partir des chaines laterales. Dans le cas du L-alanyl-glycine, on peut montrer qu'il se k~roduit unr 4limination d'hydrogene a partir du risidu glycyle et la formation d'un radical de desamination. Dans le cas du L-prolyl-L-alanine, on a observe une reaction d'ouverture de cycle (desamination), de decarboxylation et d'0limination d'un atome d'hydrogene a partir du carbone terminal en position 2.[Traduit par le journal]

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Trapping of Free Radicals formed by γ-Irradiation of Organic Compounds

Cited by 82 publications

References 8 publications

Electron spin resonance of spin-trapped radicals of amines and polyamines. Hydroxyl radical reactions in aqueous solutions and γ-radiolysis in the solid state

Electron spin resonance of spin-trapped radicals of amines and polyamines. Hydroxyl radical reactions in aqueous solutions and γ-radiolysis in the solid state

The Barton Reaction: Can a More Tenable Pathway Be Hypothesized for the Formation of Nitrosoalkyl Derivatives?

Electron spin resonance of spin trapped radicals in γ-irradiated polycrystalline dipeptides. Chromatographic separation of radicals

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