Briefly, through a series of enzymatic steps, tryptophan is normally converted into kynurenine, then to 3-hydroxykynurenine via kynurenine 3-monooxygenase (KMO; B2, NAD[P.sup.+]), then 3-hydroxyanthranilic acid
is formed by kynureninase (KYNU; B6), and proceeds down the pathway to become either acetyl-coA, picolinic acid or quinolinic acid, which is further converted into NA[D.sup.+] through another series of enzymatic steps.
Takemura et al., "3-Hydroxyanthranilic acid
, an L-tryptophan metabolite, induces apoptosis in monocyte-derived cells stimulated by interferon-y," Annals of Clinical Biochemistry, vol.
Pae, H.O., Oh, G.S., Lee, B.S., Rim, J.S., Kim, Y.M., Chung, H.T., 2006, 3-Hydroxyanthranilic acid
, one of L-tryptophan metabolites, inhibits monocyte chemoattractant protein-1 secretion and vascular cell adhesion molecule-1 expression via heme oxygenase-1 induction in human umbilical vein endothelial cells.
Curreli, "Effect of 3-hydroxyanthranilic acid
on mushroom tyrosinase activity," Biochimica etBiophysica Acta: Protein Structure and Molecular Enzymology, vol.
One molecule, 3-hydroxyanthranilic acid
, was orders of magnitude better than the others, and was selected for follow-up in the lab.
The TRP metabolites KYN, 3-HK, and 3-hydroxyanthranilic acid
(3-HAA) inhibit T-cell proliferation by a time-dependent cytotoxic action, an effect which concerns mainly not only the activated T cells, but also B and natural killer (NK) cells.
Folate (5-methyltetrahydrofolate), riboflavin, flavin mononucleotide (FMN),  FAD, pyridoxal 5'-phosphate (PLP), pyridoxal (PL), pyridoxic acid, free choline, betaine, dimethylglycine, creatinine, methionine sulfoxide, arginine, asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), tryptophan, kynurenine, kynurenic acid, anthranilic acid, 3-hydroxykynurenine, xanthurenic acid, 3-hydroxyanthranilic acid
, and formiminoglutamic acid, were determined by liquid chromatography--tandem mass spectrometry (14-17), and methylmalonic acid, total homocysteine, total cysteine, methionine, serine, glycine, cystathionine, and sarcosine by gas chromatography-tandem mass spectrometry (15, 18).
Formation of picolinic and quinolinic acids following enzymatic oxidation of 3-hydroxyanthranilic acid
. The Journal of Biological Chemistry, v.
This enzyme utilizes a non-heme Fe and dioxygen to convert 3-hydroxyanthranilic acid
(3-HAA) to 2-amino-3-carboxymuconate-6-semialdehyde (ACMS).
Specifically, 3-hydroxykynurenine (3-HK) and 3-hydroxyanthranilic acid
(3-HANA) have been studied by various research groups, which describe controversial results.
The major part of tryptophan is used for protein synthesis, in which its major catabolic route is via kynurenine and 3-hydroxyanthranilic acid
Both, 3-hydroxyanthranilic acid
(3-HANA) and 3-hydroxykynurenine (3-HK) are intermediates in the metabolism of tryptophan.