SPIN TRAPPING OF FREE RADICALS PRODUCED FROM NITROSOAMINE CARCINOGENS

Abstract— Using the spin trap 5,5-dimethylpyrroline-1-oxide we have demonstrated that the nitrosoamine carcinogen, 1-nitrosopiperidine, upon incubation with rat liver microsomes and nuclei produces two trapped free radical species. One trapped species is the hydroxyl free radical whereas the other is a free radical of unknown structure of the carcinogen itself. Three other nitrosoamine carcinogens tested, including diethylnitrosoamine, dimethylnitrosoamine and 1-nitrosopyrroline yielded similar results with the exception that the trapped carcinogen radical differs dependent upon the compound used. Oxygen was required to produce the hydroxyl free radical but its presence decreased the yield of the carcinogen radical. Both cyanide and α-tocopherol acetate caused a decrease in the yield of the carcinogen free radical. Some heat-labile inhibitor(s) of radical production was/were present in the cytosol. The amount of radical produced was not proportional to the P₄₅₀ content.