Xanthurenic Acid, Kynurenic
Acid, and Blood Sugar Regulation
To achieve more discriminative power, a biomarker group was generated including 6 upregulated (creatine, tryptophan, N-acetylhistidine, L-carnitine, pyroglutamic acid, and indoleacrylic acid) and 10 downregulated (prolinebetaine, L-acetylcarnitine, pipecolic acid, xanthurenic acid, trigonelline, kynurenic
acid, indole-3-carboxylic acid, phosphorylcholine, 4-pyridoxic acid, and thymine) metabolites with AUC > 0.85.
Liu et al., "Kynurenic
acid, an IDO metabolite, controls TSG-6-mediated immunosuppression of human mesenchymal stem cells," Cell Death & Differentiation, vol.
Quinaldic acid (0.103 mmol; 17.8 mg) or kynurenic
acid (0.103 mmol; 19.5 mg), respectively, for synthesis of complexes 1 and 2, was solubilized in 10 mL of methanol and deprotonated with triethylamine (0.132 mmol; 0.014 ml) and this solution was added dropwise on the precursor solution.
It was shown that proinflammatory cytokines, such as IL-1[beta], and reactive oxygen species can enhance the activity of IDO, which catabolizes tryptophan into kynurenine, which is further catabolized into kynurenic
acid and quinolinic acid .
The induction of IDO and TDO leads to increased concentration of kynurenine pathway metabolites, mostly kynurenic
acid and quinolinic acid.
To assess the herbs' effect on mitochondria membrane potential upon [MPP.sup.+] treatment, SH-SY5Y cells were pre-treated with NTNU-319, 379, 395 or 439 (10 [micro]g/ml) for 8 h followed by [MPP.sup.+] treatment (3.0 mM) for 24 h Kynurenic
acid (KYNA), a tryptophan metabolite known to own mitochondrial protection effect and attenuate [MPP.sup.+]-induced neuronal cell death in SH-SY5Y cells (Lee et al., 2008) was included as a positive compound for comparison.
One of the most studied metabolites of the kynurenine pathway is kynurenic
acid (KYNA), which is so far the only known endogenous NMDA receptor antagonist.
However, we showed previously that, in Goldblatt 2-kidneys, one-clip (2K1C) model, microinjection of kynurenic
acid, a broad spectrum EAA receptor antagonist, into the RVLM, reduced BP to the same extent as autonomic blockade .
A synthetic analogue of kynurenic
acid, a naturally occurring neural regulatory compound, 7-C1KYNA is one of the most potent and selective blockers of the regulatory GlyB-site of the NMDA receptor.
Schroeder et al., "Kynurenic
acid is a potent endogenous aryl hydrocarbon receptor ligand that synergistically induces interleukin-6 in the presence of inflammatory signaling," Toxicological Sciences, vol.