DESIGN OF MODIFIED PYRROLINE N-OXIDE DERIVATIVES AS SPIN TRAPS SPECIFIC FOR HYDROXYL RADICAL

Nitrones, 4-[2-(ethoxycarbonyl)ethyl]-3,3,5,5-tetramethyl-1-pyrroline N-oxide (7a) and 4-[2-(ethoxycarbonyl)ethyl]-5,5-di([H-2(3)[methyl)-3,3-dimethyl-1-pyrrolidine N-oxide (7b) have been synthesized. The ability of the nitrone (7a) to spin trap hydroxyl and superoxide radicals has been compared with nitrones 11a and 5,5-dimethyl-1-pyrroline N-oxide (DMPO, 8). Nitrone 11a bears a carbethoxy group at C-4, whereas nitrone 7a has a spacer of two methylene units between the carbethoxy and the basic nitrone ring skeleton. Nitrone 11a trapped both hydroxyl and superoxide radicals, while nitrone 7a trapped only hydroxyl radical. The hydroxyl radical adducts of 7a and 11a were more resistant toward superoxide-mediated reduction than the hydroxyl radical adduct of DMPO (8).