Sonolysis, radiolysis, and hydrogen peroxide photolysis of pyrimidine derivatives in aqueous solutions: a spin-trapping study.
The sonolysis of aqueous solutions of various dihydropyrimidines and substituted pyrimidines was investigated by ESR and spin trapping with the nonvolatile, water soluble spin trap, 3,5-dibromonitrosobenzene sulfonate (DBNBS) and its deuterated analog to examine the possibility of detecting new radicals specifically generated in the high temperature zones produced by collapsing cavitation bubbles. Similar ESR spectra were obtained from sonolysis of argon-saturated aqueous solutions, from uv photolysis of aqueous solutions containing H2O2, and from gamma radiolysis of nitrous oxide saturated solutions, although sonolysis of aqueous solutions leads to the formation of pyrimidine radicals by H atom as well as OH radical addition to the 5,6 double bond of pyrimidines. No evidence for specific new radicals formed in the high temperature regions induced by cavitation could be found. For the reactions of dihydropyrimidines with hydroxyl radicals additional spin adducts could be detected and identified with the spin trap DBNBS compared to 2-methyl-2-nitrosopropane which was used in previous studies; however, for alkylpyrimidines fewer spin adducts were observed. The use of the deuterated analog of DBNBS is helpful for unambiguous radical structure assignment.
Kondo
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Radiation Oncology Branch, National Cancer Institute, Bethesda, Maryland 20892.
Murali Krishna
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Riesz
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D001557:Benzenesulfonates; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D006861:Hydrogen Peroxide; D009603:Nitroso Compounds; D009963:Orotic Acid / Q000031:analogs & derivatives / Q000528:radiation effects; D010782:Photolysis; D011743:Pyrimidines / Q000528:radiation effects; D011830:Radiation Effects; D012996:Solutions; D013113:Spin Labels; D013941:Thymine / Q000031:analogs & derivatives / Q000528:radiation effects; D014465:Ultrasonics; D014498:Uracil / Q000031:analogs & derivatives / Q000528:radiation effects; D014867:Water
D001557:Benzenesulfonates; D005609:Free Radicals; D009603:Nitroso Compounds; D011743:Pyrimidines; D012996:Solutions; D013113:Spin Labels; D014867:Water; D014498:Uracil; D009963:Orotic Acid; C048757:3,5-dibromo-4-nitrosobenzenesulfonate; D006861:Hydrogen Peroxide; D013941:Thymine