L-kynurenine (KYN)

L-kynurenine is an endogenous amino acid derivative produced during the oxidative degradation of tryptophan via either indoleamine 2,3-dioxygenase or tryptophan dioxygenase. It serves as an important intermediate in the synthesis of several biologically active compounds including niacin/vitamin B3. L-kynurenine exhibits diverse biological activities including vasodilatory effects and significant roles in immune regulation—particularly through suppression/modulation of T-cell proliferation—and neuromodulation within the central nervous system. Aberrant production or accumulation has been linked to cognitive deficits seen in neurological diseases such as Alzheimer’s disease and Huntington’s disease; it also contributes to tumor-induced immunosuppression when overproduced by certain cancers. While not itself a direct drug target like an enzyme or receptor protein, manipulation of its metabolic pathway remains under active investigation for therapeutic intervention across oncology, neurology/psychiatry, and inflammatory disorders.

Other names

L-kynurenine(S)-2-Amino-4-(2-aminophenyl)-4-oxobutanoic acid3-Anthraniloyl-L-alanineKynurenin

Drugs act by inhibiting enzymes that produce kynurenine from tryptophan (IDO/TDO inhibition), thereby reducing immunosuppression/cancer progression. Additionally, drugs can modulate downstream metabolism to alter neuroactive metabolites—for example, by inhibiting KMO to reduce quinolinic acid synthesis, which may offer benefit in neurodegeneration. No drugs act directly on kynurenine itself.