SPIN-TRAPPING USING 2,2-DIMETHYL-2H-IMIDAZOLE-1-OXIDES

The ability of novel cyclic nitrones, 4-substituted 2,2-dimethyl-2H-im idazole-1-oxides (IMO's) to trap a variety of short-lived free radical s has been investigated using ESR spectroscopy. IMO's scavenge oxygen- , carbon- and sulfur-derived free radicals to give persistent nitroxid es. Compared to the spin trap 5,5-dimethyl-pyrroline-1-oxide, a higher lifetime of hydroxyl radical adducts and a higher selectivity related to the trapping of carbon-centered radicals was found. A reaction bet ween IMO's and superoxide was not observed. ESR parameters of 4-carbox yl-2,2-dimethyl-2H-imidazole-1-oxide (CIMO) spin adducts are highly se nsitive to the structure of the trapped radical, e.g., different spect ra were detected with radicals derived from Na2SO3 and NaHSO3. From th e data obtained, a successful application of these new spin traps in b iological systems can be expected.