Carcinogenic nitrosamines: free radical aspects of their action.
NDMA and other nitrosamines may be activated into DNA binding intermediates by a cytochrome P450-dependent formation of alpha-nitrosamino radicals or photochemically. Within the catalytic site of cytochrome P450, these radical intermediates either combine with HO. to form alpha-hydroxynitrosamines or decompose into nitric oxide and N-methylformaldimine. In the presence of phosphate, nutagenic alpha-phosphonooxy derivatives are formed from radicals generated chemically/photochemically. Studies on lipid peroxidation, in vivo and in vitro, have further suggested that radicals are formed as intermediates from N-nitrosodialkylamines. The level of nitrosamine-induced lipid peroxidation parallels hepatocarcinogenicity in rats. These data, although preliminary, provide further evidence that free radical damage and DNA alkylation are involved in carcinogenesis induced by nitrosamines.
Bartsch
H
H
Unit of Environmental Carcinogens and Host Factors, International Agency for Research on Cancer, Lyon, France.
Hietanen
E
E
Malaveille
C
C
D000818:Animals; D002273:Carcinogens; D004249:DNA Damage; D005609:Free Radicals; D009369:Neoplasms / Q000139:chemically induced; D009602:Nitrosamines / Q000494:pharmacology*
D002273:Carcinogens; D005609:Free Radicals; D009602:Nitrosamines