The N- and ring-hydroxylation of 2-acetylaminofluorene and the failure to detect N-acetylation of 2-aminofluorene in the dog.

N -Hydroxy-2-acetylaminofluorene ( N -hydroxy-AAF), in conjugated form, was identified as a urinary metabolite of 2-acetylaminofluorene (AAF) in male mongrel dogs. This metabolite was isolated and characterized in crystalline form. 7-Hydroxy-AAF, in conjugated form, and AAF were also found in the urine of dogs fed AAF; no 1-, 3-, or 5-hydroxy-AAF was detected. The ingestion of N -hydroxy-AAF led to the urinary excretion of the same metabolites; however, none of these acetylated metabolites was detected in the urine of dogs fed 2-aminofluorene, N -hydroxy-2-aminofluorene, 1-hydroxy-AAF, or 3-hydroxy-AAF. Dietary supplementation with calcium pantothenate and riboflavin and an attempt to induce acetylase activity by feeding 2-aminofluorene for several days did not lead to the urinary excretion of any recognizable acetylated urinary metabolites of 2-aminofluorene. Furthermore, under similar conditions the specific activities of the acetylated urinary metabolites of 2-(acetyl-1′-C14) aminofluorene fed in mixtures with unlabeled 2-aminofluorene were not appreciably different from the specific activity of the ingested acetyl-labeled AAF. In a dog fed a single dose of AAF-9-C14 63 per cent of the C14 was excreted in the feces, and 19 per cent of the C14 was found in the urine during the next 5 days. Approximately 3 per cent of an oral dose of AAF was found as 7-hydroxy-AAF in the feces collected during the 1st day. No N -hydroxy amides were detected in the urine of dogs after ingestion of the following amides: acetanilide and its p -vinyl, p -fluoro, and p -ethoxy derivatives; trans 4-acetylaminostilbene; 2-propionylaminofluorene; and 2- n -butyrylaminofluorene. Administration of 2-acetylaminonaphthalene to a dog led to the urinary excretion of very small amounts of this amide and its N -hydroxy metabolite. The synthesis of N -hydroxy-2-aminofluorene, a new compound, is described.