The kynurenine pathway of l-tryptophan metabolism produces several compounds of high physiological importance in the central nervous system and the immune response. Among them, cinnabarinic acid (CA) which results from the condensation of two molecules of 3-hydroxy-anthranilic acid has been identified as an activator of the metabotropic glutamate receptor (mGluR4) and the aryl hydrocarbon receptor (AhR). However, very few information was available about its stability under physiological conditions. This article shows that CA is unstable even under very soft conditions mimicking physiological conditions. Incubations in phosphate buffer pH 7.4 lead to several products coming from various reactions such as addition of H₂O on its quinone imine function, decarboxylation, and deamination. Moreover, CA rapidly reacts with glutathione (GSH), leading to adducts that result from the Michael type addition of this physiological nucleophile on the quinone imine function of CA. These preliminary results indicate that the great reactivity of CA and the nature of its various products should be considered when studying its activity towards any biological target.

L-色氨酸代谢的犬尿氨酸途径在中枢神经系统和免疫反应中产生了几种具有高度生理重要性的化合物。其中，由两分子 3-羟基邻氨基苯甲酸缩合而成的肉桂酸 (CA) 已被确定为代谢型谷氨酸受体(mGluR4) 和芳烃受体 (AhR) 的激活剂。然而，关于其在生理条件下的稳定性的信息很少。本文表明，即使在模拟生理条件的非常柔软的条件下，CA 也是不稳定的。在 pH 7.4 的磷酸盐缓冲液中孵育会产生多种来自各种反应的产物，例如在其醌亚胺功能上添加 H ₂ O、脱羧和脱氨。此外，CA 与谷胱甘肽 (GSH) 迅速反应，导致这种生理亲核试剂在 CA 的醌亚胺功能上的迈克尔型加成产生加合物。这些初步结果表明，在研究 CA 对任何生物靶标的活性时，应考虑 CA 的高反应性及其各种产物的性质。