Fluoro-substituted N-nitrosamines. 3. Microsomal metabolism of N-nitrosodibutylamine and of fluorinated analogs.

In vitro metabolism of N-nitrosodibutylamine (NDBA) and of three fluorinated analogs, N-nitroso-4,4,4-trifluorobutyl-butylamine (NDBA-F3), N-nitroso-bis(4,4,4-trifluorobutyl)-amine (NDBA-F6) AND N-nitroso-bis(2,2,3,3,4,4,4-hepafluorobutyl)amine (NDBA-F14) was investigated with rat liver microsomes. To elucidate differences in metabolism caused by fluorination, aldehydes, nitrite and unchanged nitrosamines were determined. NDBA, NDBA--F3 and NDBA-F6 were dealkylated and to a smaller extent also denitrosated. Dealkylation at the fluorinated butyl groups was reduced in comparison to the unfluorinated butyl groups. NDBA-F14 was practically unmetabolized by microsomal enzymes in vitro.