Kynurenine
l-Kynurenine is a metabolite of the amino acid l-tryptophan used in the production of niacin.
| Names | |
|---|---|
| Preferred IUPAC name
(2S)-2-Amino-4-(2-aminophenyl)-4-oxo-butanoic acid | |
| Other names
(S)-Kynurenine | |
| Identifiers | |
| |
3D model (JSmol) |
|
| ChEBI | |
| ChEMBL | |
| ChemSpider | |
| DrugBank | |
| MeSH | Kynurenine |
PubChem CID |
|
| UNII | |
| |
SMILES
| |
| Properties | |
| C10H12N2O3 | |
| Molar mass | 208.217 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references | |
Kynurenine is synthesized by the enzyme tryptophan dioxygenase, which is made primarily but not exclusively in the liver, and indoleamine 2,3-dioxygenase, which is made in many tissues in response to immune activation. Kynurenine and its further breakdown products carry out diverse biological functions, including dilating blood vessels during inflammation and regulating the immune response. Some cancers increase kynurenine production, which increases tumor growth.
Kynurenine protects the eye by absorbing UV light, especially in the UVA region (315-400 nm). Kynurenine is present in the lens and retina as one of multiple tryptophan derivatives produced in the eye, including 3-hydroxykynurenine, that together provide UV protection and aid in enhancing visual acuity. The use of kynurenine as a UV filter is consistent with its photostability and low photosensitization, owing to its efficient relaxation from the UV-induced excited state. The concentration of this UV filter decreases with age, and this loss of free kynurenine and the concomitant formation of relatively more photosensitizing kynurenine derivatives and kynurenine-protein conjugates may contribute to the formation of cataracts.
Evidence suggests that increased kynurenine production may precipitate depressive symptoms associated with interferon treatment for hepatitis C. Cognitive deficits in schizophrenia are associated with imbalances in the enzymes that break down kynurenine. Blood levels of kynurenine are reduced in people with bipolar disorder. Kynurenine production is increased in Alzheimer's disease and cardiovascular disease where its metabolites are associated with cognitive deficits and depressive symptoms. Kynurenine is also associated with tics.
Kynureninase catabolizes the conversion of kynurenine into anthranilic acid while kynurenine-oxoglutarate transaminase catabolizes its conversion into kynurenic acid. Kynurenine 3-hydroxylase converts kynurenine to 3-hydroxykynurenine.
Kynurenine has also been identified as one of two compounds that makes up the pigment that gives the goldenrod crab spider its yellow color.