Kynurenic acid (Quinurenic acid) is an endogenous tryptophan active metabolite, a triple antagonist of NMDA, glutamate, alpha7 nicotinic acetylcholine receptor, and an agonist of GPR35/CXCR8 with neuroprotective and anticonvulsant properties. It has neuroprotective and anticonvulsant properties and can be used to study neurodegeneration and metabolism-related diseases.