In vitro metabolic N-oxidation of azo compounds. II. Some factors influencing N-oxidation.

Factors affecting the metabolism of azo compounds in vitro have been studied and conditions which allow maximal metabolism established. A species difference in the extent of N-oxidation was evident, the order of activity depending on the class of substrate used. With the bisaryl azo compound, the order of activity was rabbit greater than hamster greater than mouse greater than guinea pig greater than rat, while for the bisalkyl and mixed alkyl-aryl azo compounds, the order was hamster greater than guinea pig greater than mouse greater than rabbit greater than rat. The appropriate kinetic factors, Km and Vmax, for the N-oxidation of azobenzene (AB), omega,omega'-azotoluene (AT) and omega-phenylazotoluene (PAT) are reported. A sex difference in azobenzene N-oxidase activity was observed in rats but not in hamsters.