l-kynurenine

**L-kynurenine** is a naturally occurring metabolite of the essential amino acid L-tryptophan, produced via the kynurenine pathway by the enzymes tryptophan 2,3-dioxygenase and indoleamine 2,3-dioxygenase. It serves as a precursor for niacin (vitamin B3) biosynthesis and is further metabolized into compounds such as anthranilic acid, kynurenic acid, and 3-hydroxykynurenine[1][8][9]. L-kynurenine has diverse biological functions including vasodilation during inflammation, immunoregulation through activation of the aryl hydrocarbon receptor (AHR), and neuromodulation[4][6]. It plays roles in immune response modulation by promoting naive T cell polarization to anti-inflammatory regulatory T cells via AHR agonism[4]. Elevated levels are associated with various pathological conditions such as cancer progression (by supporting tumor growth), neurodegenerative diseases like Alzheimer's disease, cognitive deficits in schizophrenia, depressive symptoms during interferon therapy for hepatitis C, frailty in aging populations, cardiovascular disease risk factors, and tics[2][5][8]. In ophthalmology research it is noted for its UV-filtering properties in the eye lens. While not an approved pharmaceutical drug or dietary supplement itself[1], it is widely used as a biochemical tool compound to study metabolism and immune regulation.

Other names

L-kynurenineKynurenine, L-3-Anthranoyl-L-alanine(S)-2-Amino-4-(2-aminophenyl)-4-oxobutanoic acid