The source of sulfate in the formation of ethereal sulfates.

Laidlaw and Young, in a recent report (l), have investigated the question of whether or not inorganic sulfate is utilized in the synthesis of ethereal sulfates. These investigators have shown, beyond any reasonable doubt, that inorganic sulfate may be utilized in the synthesis, but their data, as reported, do not permit the conclusion that inorganic sulfate of the diet is utilized to any appreciable extent in this synthesis. Several years ago, in the course of an investigation of growth and mercapturic acid formation, we were interested in ascertaining whether or not inorganic sulfate in the diet would facilitate the growth of animals receiving a phenol in the diet. We had obtained results from the feeding of bromobenzene which appeared to be consistent with a concept that as long as the dietary sulfur (cystine and methionine) was adequate, there was a constant excretion of total detoxication products (ethereal sulfates plus mercapturic acids). Dietary changes, such as the addition of extra choline (2), served to increase the excretion of mercapturic acids, but this increase of excretion of mercapturic acids appeared to be at the expense of the excretion of ethereal sulfates. It became of some importance, therefore, to determine whether the addition of inorganic sulfate to the diet would bring about a resumption of growth of rats receiving amounts of phenol sufficient to retard growth. Since bromobenzene was used in the studies of the formation of mercapturic acids, the related phenol, p-bromophenol, was used in the study of formation of ethereal sulfates. A relatively high level of p-bromophenol was necessary to bring about the cessation of growth of animals on the diet used in these studies. When growth had been stopped by the administration of p-bromophenol, it was found that inorganic sulfate was not effective in bringing about a resumption of growth, whereas cystine was very effective. In order to demonstrate that the effects on growth were correlated with the formation of ethereal sulfates certain of the animals were placed in cages permitting quantitative collection of urine, and the excretion of ethereal sulfates was determined; it was found that the addition of inorganic sulfate to the diet was ineffective in