Abstract
White and Lewis 1 in agreement with Coombs and Hele 2 demonstrated that the suggestion that in dogs “the oxidation to the phenol is a preliminary step in the synthesis of p-bromophenylmercapturic acid after the administration of bromobenzene appears improbable.” 1 These workers reported that p-bromophenol, when fed to dogs, was in part excreted as an ethereal sulphate. No appreciable effect on the excretion of the neutral sulfur in the urine was noted. This observation indicated that apparently no p-bromophenylmercapturic acid was formed from p-bromophenol.
It appeared desirable to investigate the question of the synthesis of p-bromophenylmercapturic acid from p-bromophenol in the rat, using the direct method for the estimation of mercapturic acids in the urine. Aside from the fact that such an investigation had not previously been made on the rat, we felt that apparently the question of the formation of p-bromophenol from bromobenzene as a preliminary step in the synthesis of p-bromophenylmercapturic was not as yet settled. Thus Bodansky 3 in discussing the mechanism of the synthesis of the mercapturic acid from bromobenzene, states that “the reaction involves first oxidation to p-bromophenol and its subsequent conjugation with cysteine. The resulting p-bromophenylcysteine then undergoes acetylation.” A similar statement is also made by Schmidt. 4
We administered p-bromophenol to adult white rats which were fed constant amounts of a diet of uniform composition. The urine was collected and analyzed for total sulfur, inorganic and ethereal sulfates (Folin method) and for p-bromophenylmercapturic acid. 5 The urinary values were then compared with those obtained on the same rats which ingested the same amounts of the diet free from p-bromophenol. The diet C-10 had the following composition: casein 10, cane sugar 15, corn starch 46, yeast powder 5, Osborne-Mendel salt mixture 6 4, cod liver oil 5, and Criseo 15.
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