Conjugation: Sulfation

The discovery of sulfate conjugation arose from studies on the fate of phenol. Stadeler had observed the presence of conjugated phenols in human and animal urine. Munk followed up on the studies of Schultzen and Naunyn by ingesting varying amounts of benzene, then measuring the “phenol-forming substance” in his urine by hydrolyzing the urine with hydrochloric acid and measuring the released phenol.

Others had observed the presence of indigo-forming substances in urine, characterized by the release of indigo dyes upon acid hydrolysis. Eugen Baumann isolated the indigo-forming substance and found that upon hydrolysis, in addition to the indigo, he obtained sulfuric acid—a substance not present prior to the hydrolysis.

Baumann was able to isolate and characterize phenol sulfate from the urine of a patient who had been treated with phenol as an antiseptic. He went on to show that many substances could give rise to increased sulfate excretion in the urine, including catechol, bromobenzene, indole and aniline—the latter three requiring oxidation prior to conjugation. His interest in the fate of sulfur compounds in the body led not only to the discovery of sulfate conjugation, but also to the discovery of mercapturic acid formation.

Index | Intro | The Beginning | Oxidation
Sulfation | Glucuronides | Acetylation, Methylation
Reduction | Mercapturic Acid | Founding of the Field
Drug Metabolism Methodology | In Vitro Technology | P-450
The Future

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