Indolelactic acid

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... 

Heath-Pagliuso S, Mui R, Milici A, Giese S, Chin R, Denison MS. 2000. Tryptophan metabolites, indole-3-pyrivic acid, DL-3-indolelactic acid, L-kynurenine and kynurenic acid activate Ah receptor signal transduction. Organohal. Compd. 49 289-92... 

Tryptophan can be converted to indolepyruvic acid either by oxidative deamination or by transamination (e.g., 739, 912) and the indolepyruvic acid can give rise to indoleacetic acid. The fate of indoleacetic acid formed by the bacterial flora of the mammalian gut is discussed below. Bacterial indolelactic acid (e.g., 757) is presumably derived from indolepyruvic acid, but indolelactic acid excreted by mammals (e.g. 17) may be of true mammalian rather than bacterial origin. Indolepropionic acid can also be formed by bacteria (e.g., 412, 633), but further metabolism in mammals of any indolepropionic acid formed in the gut is still obscure (904). Skatole (3-methylindole) has long been known as a product of bacterial decomposition of protein and is formed from tryptophan not only by the bacterial flora of the gut but also in putrefying secretions, e.g., sputum (756). It may well arise by decarboxylation of indoleacetic acid. 

Hydrophilic substitution in the side-chain invariably leads to the same result as e.g. for indoleglycollic (Va) and indolelactic acid (Vb) (c/. Thi-mann ). 

---