Spin trapping of O-, C-, and S-centered radicals and peroxynitrite by 2H-imidazole-1-oxides.

Spin trapping with 2H-imidazole-1-oxides (2,2,4-trimethyl-2H-imidazole-1-oxide (TMIO); 4-carboxy-2,2-dimethyl-2H-imidazole-1-oxide, potassium salt (CDMIO); 2,2-dimethyl-4-phenyl-2H-imidazole-1-oxide (DMPIO)) was studied. It was found that these compounds form spin adducts with different short lived free radicals, such as OH, CH3, CH2OH, CH3(CH)OH, C(CH3)3O, HOCH2CH2S, glutathionyl and cysteinyl radicals. 2H-imidazole-1-oxides did not trap superoxide radical. Therefore, the detection of OH and thiol radicals is not complicated by the presence of superoxide radical. It was shown that 2H-imidazole-1-oxides are effective scavengers of peroxynitrite forming the same spin adducts as with OH-radicals. Thus, TMIO, CDMIO and DMPIO can be used for spin trapping studies in chemical and biological systems.