Quinolinic acid, an excitatory kynurenine antagonized by kynurenic acid, is a choline acetyl transferase known to produce neuronal lesions in the cerebrum at low concentrations. Quinolinic acid: an endogenous metabolite that produces axon-sparing lesions in rat brain. Science.Quinolinic acid and kynurenic acid form an important balance in maintaining levels of oxidative stress. Quinolinic acid’s neurotoxicity occurs through three methods: increased glutamate signalling, acting as an N-methyl-d-aspartic acid receptor agonist, or lipid peroxidation. Picolinic acid, which is produced from 2-amino-4-carboxymuconic-6-semialdehyde in the presence of picolinic carboxylase instead of spontaneously transforming into quinolinic acid, acts as an endogenous neuroprotective agent by chelating iron, necessary for quinolinic acid to function, or zinc to antagonize quinolinic acid. Excitotoxicity of quinolinic acid: modulation by endogenous antagonists. Therefore, the balance of the kynurenine pathway metabolites is necessary to maintain normal brain function.
Since the kynurenine pathway metabolites can become sources of oxidative stress they are implicated in many neurological diseases. Metabolites, such as quinolinic acid, are commonly used to test for the neuroprotective potential of phytochemicals.