Tryptophan metabolites

Tryptophan metabolites represent a broad class of bioactive small molecules generated via the breakdown of the essential amino acid L-tryptophan through enzymatic pathways such as the kynurenine, serotonin, and indole pathways [2, 6]. These molecules, particularly kynurenine and its derivatives, serve as critical signaling mediators that influence immune homeostasis and central nervous system (CNS) activity by acting as endogenous ligands for the Aryl hydrocarbon receptor (AhR) [1, 11]. In oncology, the overproduction of immunosuppressive kynurenines by enzymes like IDO1 and TDO allows tumors to evade the immune system by inhibiting effector T cells and promoting the differentiation of regulatory T cells [3, 9, 15]. Within the CNS, an imbalance between neurotoxic metabolites (e.g., quinolinic acid) and neuroprotective ones (e.g., kynurenic acid) is implicated in the pathogenesis of neurodegenerative and psychiatric disorders, including Alzheimer's disease and depression [10, 17, 19]. Therapeutic intervention strategies focus on inhibiting the enzymes that produce these metabolites or antagonizing the receptors, such as AhR, that sense them to restore immune surveillance and neuronal health [13, 14, 20].

Other names

Kynurenine pathway metabolitesTryptophan catabolitesIndole derivativesKynureninesTrp metabolites

Modulation of immune and neuronal signaling through activation of the Aryl hydrocarbon receptor (AhR), interaction with N-methyl-D-aspartate (NMDA) and nicotinic receptors, and induction of stress-response pathways like GCN2 kinase following tryptophan depletion.