The Urinary Excretion of Mercapturic Acids after Administration of Bromobenzene and 3,4-Benzpyrene^*

Effects of bromobenzene, anthracene, and 3,4-benzpyrene on the metabolism of dl-methionine labeled with S³⁵ have been studied in the rat. Measurements of the distribution of the radioactive sulfur in the urine indicated the excretion of a mercapturic acid from bromobenzene and anthracene but not from benzpyrene. The available evidence suggests that bromobenzene interferes with the metabolism of methionine.

The contribution of tissue sulfur compounds to mercapturic acid formation was estimated after the sulfur-containing compounds of the body of the rat had been labeled by feeding radioactive methionine over a period of 15 days. The presence of appreciable amounts of “chloroform-extractable” sulfur in the urine following the ingestion of bromobenzene and anthracene confirms the view that these mercapturic acids are largely derived from tissue sulfur compounds. The data suggest the synthesis of phenanthrylmercapturic acid in vivo. No evidence could be found for the conjugation of 3,4-benzpyrene with tissue sulfur. 3,4-Benzpyrene did not interfere with the in vivo synthesis of bromophenylmercapturic acid.