N,N-dibutylnitrosamine metabolism by rat liver S9 fraction and oxidation by chemical model systems.

Oxidative in vitro metabolism of N,N-dibutylnitrosamine (DBN) by 9000g supernatant fraction (S9 fraction) prepared from rat liver and oxidation of DBN by chemical model systems (Udenfriend and Fenton) were investigated. The products retaining the N-nitroso group of DBN were analyzed by gas-liquid chromatography. Incubation of DBN with the S9 fraction gave hydroxy derivatives of DBN at the omega, omega-1, and omega-2 positions, while the chemical reaction of DBN in the Udenfriend and the Fenton model systems afforded compounds with an oxo group at the same positions. In all cases, omega-1 oxidation was predominant, followed by omega and then by omega-2 oxidations, while omega and omega-1 oxidations were the principal metabolic pathways of DBN in vivo in the rat. The differences in the oxidative transformation of DBN among in vitro enzymatic, non-enzymatic and in vivo systems are discussed.