犬尿酸是一种中间尿酸通道，被 GPR35 吸收。在 G qi/o 嵌合 G 蛋白中，磷酸肌醇合成和钙刺激是通过犬尿酸通过 GPR35 偶联机制启动的。在表达 GPR35 的细胞中，犬尿酸可增加 [35S]鸟苷 5'-O-(3-硫代三磷酸) 结合；用百日咳毒素治疗可以消除这种影响。 GPR35 内化也由犬尿酸诱导 [1]。这些化合物的毫摩尔浓度用于鉴定 KYNA 的神经调节能力以及随之而来的神经保护和抗惊厥作用。另一种可能性是 KYNA 作为内部犬尿酸盐发挥作用，具有较浅的闭合曲线和针对培养海马的非竞争性定位，如这一点及其对负责这些作用的透明离子型谷氨酸受体的影响 [NMDA，α-amino-3 -羟基-5-甲基-4-异恶唑丙酸（AMPA）和红藻碱性盐]。这些受体彼此之间的亲和力较低，并且已知大脑中的 KYNA 浓度在亚微摩尔范围内。 α7nAChRs 对神经元的 IC50 值在低微摩尔范围内 [2]。

小鼠外周血白细胞活性受犬尿酸影响；最大浓度（250 mg/L）影响最小，最低浓度（2.5 mg/L）影响最大。给动物喂酸7天和28天后，最小剂量的犬尿酸诱导T的缺血反应（p<0.05）[3]。

Metabolism / Metabolites
Uremic toxins tend to accumulate in the blood either through dietary excess or through poor filtration by the kidneys. Most uremic toxins are metabolic waste products and are normally excreted in the urine or feces.

Toxicity Summary
Uremic toxins such as kynurenic acid are actively transported into the kidneys via organic ion transporters (especially OAT3). Increased levels of uremic toxins can stimulate the production of reactive oxygen species. This seems to be mediated by the direct binding or inhibition by uremic toxins of the enzyme NADPH oxidase (especially NOX4 which is abundant in the kidneys and heart) (A7868). Reactive oxygen species can induce several different DNA methyltransferases (DNMTs) which are involved in the silencing of a protein known as KLOTHO. KLOTHO has been identified as having important roles in anti-aging, mineral metabolism, and vitamin D metabolism. A number of studies have indicated that KLOTHO mRNA and protein levels are reduced during acute or chronic kidney diseases in response to high local levels of reactive oxygen species (A7869).

[1]. Wang J, et al. Kynurenic acid as a ligand for orphan G protein-coupled receptor GPR35. J Biol Chem. 2006 Aug 4;281(31):22021-8.
[2]. Albuquerque EX, et al. Kynurenic acid as an antagonist of α7 nicotinic acetylcholine receptors in the brain: facts and challenges. Biochem Pharmacol. 2013 Apr 15;85(8):1027-32.
[3]. Małaczewska J, et al. Effect of oral administration of kynurenic acid on the activity of the peripheral blood leukocytes in mice. Cent Eur J Immunol. 2014;39(1):6-1

Kynurenic acid is a quinolinemonocarboxylic acid that is quinoline-2-carboxylic acid substituted by a hydroxy group at C-4. It has a role as a G-protein-coupled receptor agonist, a NMDA receptor antagonist, a nicotinic antagonist, a neuroprotective agent, a human metabolite and a Saccharomyces cerevisiae metabolite. It is a monohydroxyquinoline and a quinolinemonocarboxylic acid. It is a conjugate acid of a kynurenate.
Kynurenic Acid is under investigation in clinical trial NCT02340325 (FS2 Safety and Tolerability Study in Healthy Volunteers).
Kynurenic acid has been reported in Ephedra transitoria, Ephedra pachyclada, and other organisms with data available.
Kynurenic acid is a uremic toxin. Uremic toxins can be subdivided into three major groups based upon their chemical and physical characteristics: 1) small, water-soluble, non-protein-bound compounds, such as urea; 2) small, lipid-soluble and/or protein-bound compounds, such as the phenols and 3) larger so-called middle-molecules, such as beta2-microglobulin. Chronic exposure of uremic toxins can lead to a number of conditions including renal damage, chronic kidney disease and cardiovascular disease.
Kynurenic acid (KYNA) is a well-known endogenous antagonist of the glutamate ionotropic excitatory amino acid receptors N-methyl-D-aspartate (NMDA), alphaamino-3-hydroxy-5-methylisoxazole-4-propionic acid and kainate receptors and of the nicotine cholinergic subtype alpha 7 receptors. KYNA neuroprotective and anticonvulsive activities have been demonstrated in animal models of neurodegenerative diseases. Because of KYNA's neuromodulatory character, its involvement has been speculatively linked to the pathogenesis of a number of neurological conditions including those in the ageing process. Different patterns of abnormalities in various stages of KYNA metabolism in the CNS have been reported in Alzheimer's disease, Parkinson's disease and Huntington's disease. In HIV-1-infected patients and in patients with Lyme neuroborreliosis a marked rise of KYNA metabolism was seen. In the ageing process KYNA metabolism in the CNS of rats shows a characteristic pattern of changes throughout the life span. A marked increase of the KYNA content in the CNS occurs before the birth, followed by a dramatic decline on the day of birth. A low activity was seen during ontogenesis, and a slow and progressive enhancement occurs during maturation and ageing. This remarkable profile of KYNA metabolism alterations in the mammalian brain has been suggested to result from the development of the organisation of neuronal connections and synaptic plasticity, development of receptor recognition sites, maturation and ageing. There is significant evidence that KYNA can improve cognition and memory, but it has also been demonstrated that it interferes with working memory. Impairment of cognitive function in various neurodegenerative disorders is accompanied by profound reduction and/or elevation of KYNA metabolism. The view that enhancement of CNS KYNA levels could underlie cognitive decline is supported by the increased KYNA metabolism in Alzheimer's disease, by the increased KYNA metabolism in down's syndrome and the enhancement of KYNA function during the early stage of Huntington's disease. Kynurenic acid is the only endogenous N-methyl-D-aspartate (NMDA) receptor antagonist identified up to now, that mediates glutamatergic hypofunction. Schizophrenia is a disorder of dopaminergic neurotransmission, but modulation of the dopaminergic system by glutamatergic neurotransmission seems to play a key role. Despite the NMDA receptor antagonism, kynurenic acid also blocks, in lower doses, the nicotinergic acetycholine receptor, i.e., increased kynurenic acid levels can explain psychotic symptoms and cognitive deterioration. Kynurenic acid levels are described to be higher in the cerebrospinal fluid (CSF) and in critical central nervous system (CNS) regions of schizophrenics as compared to controls. (A3279, A3280).
Kynurenic acid is a metabolite found in or produced by Saccharomyces cerevisiae.
A broad-spectrum excitatory amino acid antagonist used as a research tool.

C10H7NO3

189.17

189.042

492-27-3

Kynurenic acid-d5;350820-13-2;Kynurenic acid sodium;2439-02-3

3845

Light yellow to yellow solid powder

1.4±0.1 g/cm3

358.4±42.0 °C at 760 mmHg

275 °C (dec.)(lit.)

170.5±27.9 °C

0.0±0.8 mmHg at 25°C

1.639

2.28

70.42

2

4

1

14

309

0

O=C1C([H])=C(C(=O)O[H])N([H])C2=C([H])C([H])=C([H])C([H])=C21

HCZHHEIFKROPDY-UHFFFAOYSA-N

InChI=1S/C10H7NO3/c12-9-5-8(10(13)14)11-7-4-2-1-3-6(7)9/h1-5H,(H,11,12)(H,13,14)

4-oxo-1H-quinoline-2-carboxylic acid

Kynuronic acid; Kynurenic acid; Kynurenic acid

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

0.1 M NaOH : ~12.5 mg/mL (~66.08 mM)
DMSO : ~9 mg/mL (~47.58 mM)
H2O : < 0.1 mg/mL

配方 1 中的溶解度: ≥ 1.25 mg/mL (6.61 mM) (饱和度未知) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (这些助溶剂从左到右依次添加，逐一添加), 澄清溶液。
例如，若需制备1 mL的工作液，可将100 μL 12.5 mg/mL澄清的DMSO储备液加入到400 μL PEG300中，混匀；再向上述溶液中加入50 μL Tween-80，混匀；然后加入450 μL生理盐水定容至1 mL。
*生理盐水的制备：将 0.9 g 氯化钠溶解在 100 mL ddH₂O中，得到澄清溶液。

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配方 2 中的溶解度: ≥ 1.25 mg/mL (6.61 mM) (饱和度未知) in 10% DMSO + 90% Corn Oil (这些助溶剂从左到右依次添加，逐一添加), 澄清溶液。
例如，若需制备1 mL的工作液，可将 100 μL 12.5 mg/mL 澄清 DMSO 储备液加入到 900 μL 玉米油中并混合均匀。

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配方 3 中的溶解度: 33.33 mg/mL (176.19 mM) in 50% PEG300 50% Saline (这些助溶剂从左到右依次添加，逐一添加), 悬浊液; 超声助溶。
*生理盐水的制备：将 0.9 g 氯化钠溶解在 100 mL ddH₂O中，得到澄清溶液。

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请根据您的实验动物和给药方式选择适当的溶解配方/方案：
1、请先配制澄清的储备液(如：用DMSO配置50 或 100 mg/mL母液(储备液));
2、取适量母液，按从左到右的顺序依次添加助溶剂，澄清后再加入下一助溶剂。以 下列配方为例说明 (注意此配方只用于说明，并不一定代表此产品 的实际溶解配方):
10% DMSO → 40% PEG300 → 5% Tween-80 → 45% ddH2O (或 saline);
假设最终工作液的体积为 1 mL, 浓度为5 mg/mL: 取 100 μL 50 mg/mL 的澄清 DMSO 储备液加到 400 μL PEG300 中，混合均匀/澄清；向上述体系中加入50 μL Tween-80，混合均匀/澄清；然后继续加入450 μL ddH2O (或 saline)定容至 1 mL；
3、溶剂前显示的百分比是指该溶剂在最终溶液/工作液中的体积所占比例;
4、 如产品在配制过程中出现沉淀/析出，可通过加热(≤50℃)或超声的方式助溶;
5、为保证最佳实验结果，工作液请现配现用！
6、如不确定怎么将母液配置成体内动物实验的工作液，请查看说明书或联系我们;
7、 以上所有助溶剂都可在 Invivochem.cn网站购买。