3Hydroxyanthranilate

3-hydroxyanthranilate, also referred to as 3-hydroxyanthranilic acid in its protonated form or as its anion at physiological pH, is a hydroxy-substituted benzoate derived from the breakdown of tryptophan. It is an intermediate in the kynurenine pathway, a major route for tryptophan catabolism in mammals and many other organisms.

In the kynurenine pathway, 3-hydroxykynurenine is cleaved by kynureninase to yield 3-hydroxyanthranilate and alanine. 3-Hydroxyanthranilate then serves as a substrate for the enzyme 3-hydroxyanthranilate 3,4-dioxygenase, which converts it to 2-amino-3-carboxymuconic semialdehyde (ACMS). ACMS can spontaneously cyclize to quinolinic acid, a precursor in the biosynthesis of nicotinamide adenine dinucleotide (NAD+). Thus, 3-hydroxyanthranilate lies downstream of several steps that connect tryptophan metabolism to NAD+ production.

Biologically, the kynurenine pathway and its intermediates, including 3-hydroxyanthranilate and quinolinic acid, have relevance to neurobiology and inflammation. Quinolinic acid is an NMDA receptor agonist and can contribute to excitotoxic stress under certain conditions, linking pathway flux to neurodegenerative and inflammatory states. As an intermediate, 3-hydroxyanthranilate is often studied in biochemistry and analytical chemistry contexts to understand pathway regulation and to monitor metabolic changes in tissues and biofluids.

Chemically, the compound exists predominantly as the anion form at physiological pH and is characterized by a carboxylate group, an amino group, and a hydroxyl substituent on the benzoate ring. It is used in enzyme assays and metabolic studies to investigate kynurenine pathway dynamics.