ESR of spin-trapped radicals in aqueous solutions of dihydropyrimidine bases. [Gamma radiation]
The reactions of hydroxyl radicals with several dihydropyrimidine base derivatives in aqueous solutions have been investigated by the technique of spin-trapping and ESR spectroscopy. Hydroxyl radicals were generated by the uv photolysis of H/sub 2/O/sub 2/ and tertiary nitrosobutane was used as the spin trapping reagent. The dihydro derivatives of uracil, 6-methyluracil, 1-methyluracil, 1-ethyluracil, 1-methylcytosine, 5-methylcytosine, thymine, and orotic acid were investigated. The predominant reaction in all cases was the abstraction of the H atoms bound to the C(6) position. To a lesser extent H-abstraction took place from the methyl groups attached to the N(1), C(5), and C(6) positions. For dihydro-1-ethyluracil, H atoms were abstracted from both the carbon atoms of the ethyl group. The radicals produced by H-abstraction from the C(5) or C(6) positions of the dihydropyrimidines are equivalent to those formed by H atom addition to the C(5) to C(6) double bonds of the corresponding pyrimidines. Hence the present results are helpful in distinguishing between the spin-trapped radicals formed by H or OH addition to the C(5) to C(6) double bond of pyrimidines of ..gamma..-irradiated aqueous solutions.
- Research Organization:
- National Inst. of Health, Bethesda, MD
- OSTI ID:
- 6670939
- Journal Information:
- Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 75:1; ISSN RAREA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
AMINES
AQUEOUS SOLUTIONS
AZINES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CYTOSINE
DECOMPOSITION
DISPERSIONS
ELECTROMAGNETIC RADIATION
ELECTRON SPIN RESONANCE
GAMMA RADIATION
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYDROGEN PEROXIDE
HYDROXY COMPOUNDS
HYDROXYL RADICALS
IONIZING RADIATIONS
KINETICS
MAGNETIC RESONANCE
MIXTURES
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OROTIC ACID
OXYGEN COMPOUNDS
PEROXIDES
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
PYRIMIDINES
RADIATION EFFECTS
RADIATIONS
RADICALS
REACTION KINETICS
RESONANCE
SOLUTIONS
SPECTROSCOPY
THYMINE
URACILS