Reactions between hydroxyl-radical-induced 7,8-dihydro-8-oxo-2'-deoxyguanosine precursor and the spin trap alpha-phenyl-N-tert-butylnitrone.
An N2O-saturated aqueous solution containing 2'-dG and the spin trap agent PBN was examined by ESR and HPLC-ECD methods after X irradiation. ESR examination showed that the ESR spectrum obtained consisted of signals due to the PBN-OH and PBN-H adducts. The signal intensity of PBN-H adducts was larger in the presence of 2'-dG than in the absence of 2'dG, while that of PBN-OH adducts was smaller in the presence of 2'-dG than in the absence of 2'-dG. When the OH-radical-induced 8-oxodG was measured by HPLC-ECD, the yield of 8-oxodG was found to be enhanced about twofold in the presence of PBN. By contrast, usual OH-radical scavengers (DMSO, sodium formate and mannitol) inhibited the formation of 8-oxodG beyond expectation. The enhancement of the yield of PBN-H adducts by 2'-dG and the enhancement of the 8-oxodG formation by PBN were explained by the electron transfer and subsequent proton transfer reactions from OH-radical-induced guanine-N7 radicals to PBN to form 8-oxodG and PBN-H. The present study led us to conclude that PBN reacted with the precursor radical of 8-oxodG to accelerate the formation of 8-oxodG, while OH-radical scavengers reacted with it to diminish the formation of 8-oxodG.
Ohshima
H
H
Laboratory of Radiation Biology, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
Ono
A
A
Matsuda
A
A
Sawamura
S
S
Kuwabara
M
M
D000080242:8-Hydroxy-2'-Deoxyguanosine; D002851:Chromatography, High Pressure Liquid; D003497:Cyclic N-Oxides; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000528:radiation effects; D004563:Electrochemistry; D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers; D017665:Hydroxyl Radical / Q000737:chemistry; D066298:In Vitro Techniques; D009589:Nitrogen Oxides / Q000737:chemistry*; D013113:Spin Labels
D003497:Cyclic N-Oxides; D016166:Free Radical Scavengers; D009589:Nitrogen Oxides; D013113:Spin Labels; D017665:Hydroxyl Radical; C029217:phenyl-N-tert-butylnitrone; D000080242:8-Hydroxy-2'-Deoxyguanosine; D003849:Deoxyguanosine