Metabolism of N-nitrosomorpholine by the rat in vivo and by rat liver microsomes and its oxidation by the Fenton system.

N-Nitrosomorpholine is converted into N-nitroso-2-hydroxymorpholine by rat liver microsomes and by the Fenton oxidation system. The hydroxy derivative was also synthesised by the oxidation of N-nitrosodiethanolamine with permanganate and characterized as the methoxime and the 2,4-dinitrophenylhydrazone. The Fenton system also afforded products believed to be N-nitroso-2-morpholone, and the 2-hydroperoxy- and 2-peroxy-derivatives of N-nitrosomorpholine. The only urinary metabolite definitely identified was N-nitrosodiethanolamine. The significance of metabolic 2-hydroxylation in relation to the carcinogenic action of N-nitrosomorpholine is discussed.