Indican excretion

A compound formed by the action of bacteria in the gut on dietary tryptophan. It is absorbed from the gut and subsequently excreted in the urine. Increased bacterial activity in the gut (e.g. in blood loop syndrome or inestinal stagnation) results in increased urinary indican excretion. 

An adolescent developed a persistent scaly and dirty-looking rash and severe neurologic symptoms, such as difficulty in walking and maintaining balance. He was in and out of the hospital for several years with no relief. His laboratory data showed increased levels of serum bicarbonate (31 meq/L), normal urinary porphyrins and porphobilinogen, and a massive excretion of amino acids, indican, and indoxyl sulfate. 

Metabolic studies by Milne et al. (M8) showed that in Hartnup disease the renal aminoaciduria is more constant than the excessive excretion of indican and indolic acids (indoleacetic acid, indolelactic acid, and indoleacetylglutamine). After ingestion of L-tryptophan in this disease there is usually delayed and incomplete absorption from the gut of the amino acid which is partly converted, by intestinal bacteria, to indole... 

Indole absorbed from the gut is hydroxylated to form indoxyl, which conjugates with sulfate to produce indican (indoxylsulfuric acid) in the liver. Indoxyl and indican are found in human plasma and urine. The daily urinary excretion of indoxylsulfate in normal adults was reported to average 200 mg (range 140-250 mg). Indole was not detected in the blood of rabbits exposed at 10mgm for 3h. 

Urinary indican is the 0-sulfate of indoxyl (usually isolated as the potassium salt, 414) and is excreted by mammals as a detoxication product of the... 

Urinary indole profile Larger excretion of 5-hydroxyindole acetic acid, 5-hydroxy tryptamine, and kynurenine are consistently present but indican is absent 48,135, 229... 

Chromatography revealed excretion of a number of amino acids in his urine, with abnormally high concentrations of tryptophan, phenylalanine, tyrosine, leucine, isoleucine and valine. His urine also contained relatively high concentrations of a number of indolic compounds, including indoxyl sulphate (indican), indolyllactate, indolylacetate, indolylacetamide and indolylacetylglutamine, which are not detectable in the urine of normal subjects. 

The sulfate group can be transferred easily, i.e. in exergonic reactions, to phenols and alcohols. These sulfuric esters have long been known as detoxication and excretion forms of various foreign substances and metabolic products. They include phenol sulfuric acid, indoxyl sulfuric acid (indican), and estrone sulfuric acid. The sulfuric esters of carbohydrates arise presumably in a similar manner (Chapt. XVII-7). 

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