gc-1

NH-3 is a potent orally active thyroid hormone receptor (THR) antagonist which exhibits reversible behavior, demonstrated by an IC 50 of 55 nM. Derived from the selective thyromi-metic GC-1, NH-3 effectively inhibits the binding of thyroid hormones to their respective receptors, resulting in hindered cofactor recruitment.

Sobetirome (IACS-010759) is a selective agonist of thyroid hormone receptor β (TRβ) and binds selectively to TRβ-1 (EC50: 0.16 μM).

CGC-11047 free base is a second generation polyamine analogue of N1, N12-bisethylspermine (BESpm).

13C15-Nivalenol is intended for use as an internal standard for the quantification of nivalenol by GC- or LC-MS. Nivalenol is a trichothecene mycotoxin that has been found inFusarium.1It is lethal to mice (LD50= 6.9 mg/kg).2Nivalenol (5, 10, and 15 mg/kg) also induces thymic, splenic, and Peyer's patch cell apoptosis in mice.3 1.Yang, Z., Concannon, J., Ng, K.S., et al.Tetrandrine identified in a small molecule screen to activate mesenchymal stem cells for enhanced immunomodulationSci. Rep.630263(2016) 2.Yoshizawa, T., and Morooka, N.Studies on the toxic substances in the infected cereals (part 3): Acute toxicities of new trichothecene mycotoxins: Deoxynivalenol and its monoacetateJ. Food Hyg.15(4)261-269(1974) 3.Poapolathep, A., Ohtsuka, R., Kiatipattanasakul, W., et al.Nivalenol-induced apoptosis in thymus, spleen and Peyer's patches of miceExp. Toxicol. Pathol.53(6)441-446(2002)

3-Acetyldeoxy nivalenol-13C17is intended for use as an internal standard for the quantification of 3-acetyldeoxy nivalenol by GC- or LC-MS. 3-Acetyldeoxy nivalenol is a mycotoxin that has been found inF. graminearum.1In vivo, 3-acetyldeoxy nivalenol (40 mg/kg) induces duodenal and splenic cell necrosis, as well as lethality (LD50= 70 mg/kg) in mice.2 1.Jiao, F., Kawakami, A., and Nakajima, T.Effects of different carbon sources on trichothecene production and Tri gene expression by Fusarium graminearum in liquid cultureFEMS Microbiol.Lett.285(2)212-219(2008) 2.Schiefer, H.B., Nicholson, S., Kasali, O.B., et al.Pathology of acute 3-acetyldeoxynivalenol toxicity in miceCan. J. Comp. Med.49(3)315-318(1985)

4-deoxy Nivalenol-13C15is intended for use as an internal standard for the quantification of 4-deoxy nivalenol by GC- or LC-MS. 4-deoxy Nivalenol is a trichothecene mycotoxin that has been found inFusarium.1It binds to eukaryotic ribosomes and inhibits protein synthesis in mice when administered at doses ranging from 5 to 25 mg/kg. 4-deoxy Nivalenol (0.1 and 0.2 mg/kg) induces emesis in pigs and decreases feed consumption in pigs when administered at a dose of 40 ppb in the diet.2It induces lethality in mice (LD50= 46-78 mg/kg).34-deoxy Nivalenol has been found inF. graminearum-infected cereal grains such as wheat, barley, and corn. 1.Pestka, J.J., and Smolinski, A.T.Deoxynivalenol: Toxicology and potential effects on humansJ.Toxicol.Environ.Health B.Crit.Rev.8(1)39-69(2005) 2.Forsyth, D.M., Yoshizawa, T., Morooka, N., et al.Emetic and refusal activity of deoxynivalenol to swineAppl. Environ. Microbiol.34(5)547-552(1977) 3.Pestka, J.J.Deoxynivalenol: Mechanisms of action, human exposure, and toxicological relevanceArch. Toxicol.84(9)663-679(2010)

Aflatoxin B2-13C17(AFB2-13C17) is intended for use as an internal standard for the quantification of AFB2by GC- or LC-MS. AFB2is a mycotoxin that has been found inA. terricola.1It induces hepatic autophagy and apoptosis in broiler chickens when administered at doses of 0.2, 0.4, and 0.8 mg/kg.2AFB2(0.5 and 1 mg/animal) also induces parenchymal cell hyperplasia in rats.3 1.Moubasher, A.H., el-Kady, I.A., and Shoriet, A.Toxigenic Aspergilli isolated from different sources in EgyptAnn. Nutr. Aliment.31(4-6)607-615(1977) 2.Chen, B., Li, D., Li, M., et al.Induction of mitochondria-mediated apoptosis and PI3K/Akt/mTOR-mediated autophagy by aflatoxin B2 in hepatocytes of broilersOncotarget7(51)84989-84998(2016) 3.Wogan, G.N., Edwards, G.S., and Newberne, P.M.Structure-activity relationships in toxicity and carcinogenicity of aflatoxins and analogsCancer Res.31(12)1936-1942(1971)

Aflatoxin G1-13C17is intended for use as an internal standard for the quantification of aflatoxin G1by GC- or LC-MS. Aflatoxin G1is a mycotoxin that has been found inA. terricola.1In vivo, aflatoxin G1is lethal to ducklings (LD50= 1.18 mg/kg).2It induces hepatocellular carcinoma tumor formation and lethality in rats when administered at doses of 1.4 and 3 mg/animal, respectively. Aflatoxin G1also inhibits liver and kidney succinate dehydrogenase and fumarase, as well as kidney cytochrome oxidase, NADH oxidase, α-glycerophosphate dehydrogenase, isocitrate dehydrogenase, and malate dehydrogenase in rats.3 1.Moubasher, A.H., el-Kady, I.A., and Shoriet, A.Toxigenic Aspergilli isolated from different sources in EgyptAnn. Nutr. Aliment.31(4-6)607-615(1977) 2.Wogan, G.N., Edwards, G.S., and Newberne, P.M.Structure-activity relationships in toxicity and carcinogenicity of aflatoxins and analogsCancer Res.31(12)1936-1942(1971) 3.Bai, N.J., Pai, M.R., and Venkitasubramanian, T.A.Mitochondrial function in aflatoxin toxicityIndian J. Biochem. Biophys.14(4)347-349(1977)

Aflatoxin G2-13C17is intended for use as an internal standard for the quantification of aflatoxin G2by GC- or LC-MS. Aflatoxin G2is a mycotoxin that has been found inAspergillus.1It is lethal to ducklings (LD50= 2.83 mg/kg) but is non-toxic to rats when administered at a dose of 200 mg/kg.2 1.Bennett, J.W., and Klich, M.MycotoxinsClin. Microbiol. Rev.16(3)497-516(2003) 2.Wogan, G.N., Edwards, G.S., and Newberne, P.M.Structure-activity relationships in toxicity and carcinogenicity of aflatoxins and analogsCancer Res.31(12)1936-1942(1971)

Guanfacine-13C,15N3is intended for us as an internal standard for the quantification of guanfacine by GC- or LC-MS. Guanfacine is an α2-adrenergic receptor (α2-AR) agonist with Kivalues of 93, 1,380, and 3,890 nM for α2A-, α2B-, and α2C-ARs, respectively, in a radioligand binding assay.1It has EC50values of 52, 288, and 602 nM for α2A-, α2B-, and α2C-ARs, respectively, for stimulated [35S]GTPγS binding. It also binds to imidazoline receptor 1 (Ki= 19 nM in a radioligand binding assay).2Guanfacine (0.3-5 mg/kg) binds to adrenergic receptors in the central nervous system and lowers blood pressure in hypertensive rats in a dose-dependent manner.3It also improves spatial working memory deficits induced by hypobaric hypoxia in rats.4Formulations containing guanfacine are used in the treatment of high blood pressure and attention deficit hyperactivity disorder (ADHD). 1.Jasper, J.R., Lesnick, J.D., Chang, L.K., et al.Ligand efficacy and potency at recombinant α2 adrenergic receptors: Agonist-mediated [35S]GTPγS bindingBiochem. Pharmacol.55(7)1035-1043(1998) 2.Nikolic, K., Filipic, S., and Agbaba, D.QSAR study of imidazoline antihypertensive drugsBioorg. Med. Chem.16(15)7134-7140(2008) 3.Scholtysik, G.Pharmacology of guanfacineBr. J. Clin. Pharmacol.10(Suppl 1)21S-24S(1980) 4.Kauser, H., Sahu, S., Kumar, S., et al.Guanfacine is an effective countermeasure for hypobaric hypoxia-induced cognitive declineNeuroscience254110-119(2013)

2-deoxy-D-Glucose-13C6is intended for use as an internal standard for the quantification of 2-deoxy-D-glucose by GC- or LC-MS. 2-deoxy-D-Glucose is a glucose antimetabolite and an inhibitor of glycolysis.1,2It inhibits hexokinase, the enzyme that converts glucose to glucose-6-phosphate, as well as phosphoglucose isomerase, the enzyme that converts glucose-6-phosphate to fructose-6-phosphate.32-deoxy-D-Glucose (16 mM) induces apoptosis in SK-BR-3 cells, as well as inhibits the growth of 143B osteosarcoma cells cultured under hypoxic conditions when used at a concentration of 2 mg ml.4,5In vivo, 2-deoxy-D-glucose (500 mg kg) reduces tumor growth in 143B osteosarcoma and MV522 non-small cell lung cancer mouse xenograft models when used alone or in combination with doxorubicin or paclitaxel .6 1.Kang, H.T., and Hwang, E.S.2-Deoxyglucose: An anticancer and antiviral therapeutic, but not any more a low glucose mimeticLife Sci.78(12)1392-1399(2006) 2.Aft, R.L., Zhang, F.W., and Gius, D.Evaluation of 2-deoxy-D-glucose as a chemotherapeutic agent: Mechanism of cell deathBr. J. Cancer87(7)805-812(2002) 3.Ralser, M., Wamelink, M.M., Struys, E.A., et al.A catabolic block does not sufficiently explain how 2-deoxy-D-glucose inhibits cell growthProc. Natl. Acad. Sci. USA105(46)17807-17811(2008) 4.Liu, H., Savaraj, N., Priebe, W., et al.Hypoxia increases tumor cell sensitivity to glycolytic inhibitors: A strategy for solid tumor therapy (Model C)Biochem. Pharmacol.64(12)1745-1751(2002) 5.Zhang, X.D., Deslandes, E., Villedieu, M., et al.Effect of 2-deoxy-D-glucose on various malignant cell lines in vitroAnticancer Res.26(5A)3561-3566(2006) 6.Maschek, G., Savaraj, N., Priebe, W., et al.2-deoxy-D-glucose increases the efficacy of adriamycin and paclitaxel in human osteosarcoma and non-small cell lung cancers in vivoCancer Res.64(1)31-34(2004)

Oleic acid-13C is intended for use as an internal standard for the quantification of oleic acid by GC- or LC-MS. Oleic acid is a monounsaturated fatty acid and a major component of membrane phospholipids that has been found in human plasma, cell membranes, and adipose tissue.1,2 It contributes approximately 17% of the total fatty acids esterified to phosphatidylcholine, the major phospholipid class in porcine platelets.1 Oleic acid inhibits collagen-stimulated platelet aggregation by approximately 90% when used at a concentration of 10 μg/ml. It also inhibits fMLF-induced neutrophil aggregation and degranulation by 55 and 68%, respectively, when used at a concentration of 5 μM, similar to arachidonic acid .3 Oleic acid (60 μM) induces release of intracellular calcium in human platelets.4

Octanoic acid-13C is intended for use as an internal standard for the quantification of octanoic acid by GC- or LC-MS. Octanoic acid is a medium-chain saturated fatty acid. It has been found in Teleme cheeses made from goat, ovine, or bovine milk.1 Octanoic acid is active against the bacteria S. mutans, S. gordonii, F. nucleatum, and P. gingivalis (IC80s = <125, <125, 1,403, and 2,294 μM, respectively).2 Levels of octanoic acid are increased in the plasma of patients with medium-chain acyl-CoA dehydrogenase (MCAD) deficiency, an inborn error of fatty acid metabolism characterized by hypoketotic hypoglycemia, medium-chain dicarboxylic aciduria, and intolerance to fasting.3,4 |1. Mallatou, H., Pappa, E., and Massouras, T. Changes in free fatty acids during ripening of Teleme cheese made with ewes', goats', cows' or a mixture of ewes' and goats' milk. Int. Dairy J. 13(1-3), 211-219 (2003).|2. Hyang, C.B., Alimova, Y., Myers, T.M., et al. Short- and medium-chain fatty acids exhibit antimicrobial activity for oral microorganisms. Arch. Oral Biol. 56(7), 650-654 (2011).|3. Onkenhout, W., Venizelos, V., van der Poel, P.F.H., et al. Identification and quantification of intermediates of unsaturated fatty acid metabolism in plasma of patients with fatty acid oxidation disorders. Clin. Chem. 41(10), 1467-1474 (1995).|4. Rinaldo, P., O'Shea, J.J., Coates, P.M., et al. Medium-chain acyl-CoA dehydrogenase deficiency. Diagnosis by stable-isotope dilution measurement of urinary n-hexanoylglycine and 3-phenylpropionylglycine. N. Engl. J. Med. 319(20), 1308-1313 (1988).

HT-2 toxin-13C22is intended for use as an internal standard for the quantification of HT-2 toxin by GC- or LC-MS. HT-2 toxin is a type A trichothecene mycotoxin and an active, deacetylated metabolite of the trichothecene mycotoxin T-2 toxin .1,2Like T-2 toxin, HT-2 toxin inhibits protein synthesis and cell proliferation in plants.2HT-2 toxin also reduces viability of HepG2, A549, HEp-2, Caco-2, A-204, U937, Jurkat, and RPMI-8226 cancer cells with IC50values ranging from 3.1 to 23 ng/ml and human umbilical vein endothelial cells with an IC50value of 56.4 ng/ml.1It induces oxidative stress, DNA damage, and autophagy in, as well as halts the development of, cultured mouse embryos when used at a concentration of 10 nM.3HT-2 toxin has been found in cereal grains and food products.4,5 1.Nielsen, C., Casteel, M., Didier, A., et al.Trichothecene-induced cytotoxicity on human cell linesMycotoxin Res.25(2)77-84(2009) 2.Nathanail, A.V., Varga, E., Meng-Reiterer, J., et al.Metabolism of the fusarium mycotoxins T-2 toxin and HT-2 toxin in wheatJ. Agric. Food Chem.63(35)7862-7872(2015) 3.Zhang, L., Li, L., Xu, J., et al.HT-2 toxin exposure induces mitochondria dysfunction and DNA damage during mouse early embryo developmentReprod. Toxicol.85104-109(2019) 4.Langseth, W., and Rundberget, T.The occurrence of HT-2 toxin and other trichothecenes in Norwegian cerealsMycopathologia147(3)157-165(1999) 5.Al-Taher, F., Cappozzo, J., Zweigenbaum, J., et al.Detection and quantitation of mycotoxins in infant cereals in the U.S. market by LC-MS/MS using a stable isotope dilution assayFood Control72(Part A)27-35(2017)

Palmitic acid-13C is intended for use as an internal standard for the quantification of palmitic acid by GC- or LC-MS. Palmitic acid is a 16-carbon saturated fatty acid. It comprises approximately 25% of human total plasma lipids.1 It increases protein levels of COX-2 in RAW 264.7 cells when used at a concentration of 75 μM.2 Palmitic acid is involved in the acylation of proteins to anchor membrane-bound proteins to the lipid bilayer.2,3,4,5,6 |1. Santos, M.J., López-Jurado, M., Llopis, J., et al. Influence of dietary supplementation with fish oil on plasma fatty acid composition in coronary heart disease patients. Ann. Nutr. Metab. 39(1), 52-62 (1995).|2. Lee, J.Y., Sohn, K.H., Rhee, S.H., et al. Saturated fatty acids, but not unsaturated fatty acids, induced the expression of cyclooxygenase-2 mediated through toll-like receptor 4. J. Biol. Chem. 276(20), 16683-16689 (2001).|3. Dietzen, D.J., Hastings, W.R., and Lublin, D.M. Caveolin is palmitoylated on multiple cysteine residues. Palmitoylation is not necessary for localization of caveolin to caveolae. J. Biol. Chem. 270(12), 6838-6842 (1995).|4. Robinson, L.J., and Michel, T. Mutagenesis of palmitoylation sites in endothelial nitric oxide synthase identifies a novel motif for dual acylation and subcellular targeting. Proc. Nat. Acad. Sci. USA 92(25), 11776-11780 (1995).|5. Topinka, J.R., and Bredt, D.S. N-terminal palmitoylation of PSD-95 regulates association with cell membranes and interaction with K+ channel Kv1.4. Neuron 20(1), 125-134 (1998).|6. Miggin, S.M., Lawler, O.A., and Kinsella, B.T. Palmitoylation of the human prostacyclin receptor. Functional implications of palmitoylation and isoprenylation. J. Biol. Chem. 278(9), 6947-6958 (2003).

Palmitic acid-13C (C1, C2, C3, and C4 labeled) is intended for use as an internal standard for the quantification of palmitic acid by GC- or LC-MS. Palmitic acid is a common 16-carbon saturated fat that represents 10-20% of human dietary fat intake and comprises approximately 25 and 65% of human total plasma lipids and saturated fatty acids, respectively.1,2Acylation of palmitic acid to proteins facilitates anchoring of membrane-bound proteins to the lipid bilayer and trafficking of intracellular proteins, promotes protein-vesicle interactions, and regulates various G protein-coupled receptor functions.1Red blood cell palmitic acid levels are increased in patients with metabolic syndrome compared to patients without metabolic syndrome and are also increased in the plasma of patients with type 2 diabetes compared to individuals without diabetes.3,4 1.Fatima, S., Hu, X., Gong, R.-H., et al.Palmitic acid is an intracellular signaling molecule involved in disease developmentCell. Mol. Life Sci.76(13)2547-2557(2019) 2.Santos, M.J., López-Jurado, M., Llopis, J., et al.Influence of dietary supplementation with fish oil on plasma fatty acid composition in coronary heart disease patientsAnn. Nutr. Metab.39(1)52-62(1995) 3.Yi, L.-Z., He, J., Liang, Y.-Z., et al.Plasma fatty acid metabolic profiling and biomarkers of type 2 diabetes mellitus based on GC/MS and PLS-LDAFEBS Lett.580(30)6837-6845(2006) 4.Kabagambe, E.K., Tsai, M.Y., Hopkins, P.N., et al.Erythrocyte fatty acid composition and the metabolic syndrome: A National Heart, Lung, and Blood Institute GOLDN studyClin. Chem.54(1)154-162(2008)

Palmitic acid-13C is intended for use as an internal standard for the quantification of palmitic acid by GC- or LC-MS. Palmitic acid-13C contains 13C at the C2 position and has been used in the study of free fatty acid incorporation into phospholipid fatty acids in soil microbes.1 Palmitic acid is a 16-carbon saturated fatty acid. It comprises approximately 25% of human total plasma lipids.2 It increases protein levels of COX-2 in RAW 264.7 cells when used at a concentration of 75 μM.3 Palmitic acid is involved in the acylation of proteins to anchor membrane-bound proteins to the lipid bilayer.3,4,5,6,7 |1. Dippold, M.A., and Kuzyakov, Y. Direct incorporation of fatty acids into microbial phospholipids in soils: Position-specific labeling tells the story. Geochim. Cosmochim. Acta 174(1), 211-221 (2016).|2. Santos, M.J., López-Jurado, M., Llopis, J., et al. Influence of dietary supplementation with fish oil on plasma fatty acid composition in coronary heart disease patients. Ann. Nutr. Metab. 39(1), 52-62 (1995).|3. Lee, J.Y., Sohn, K.H., Rhee, S.H., et al. Saturated fatty acids, but not unsaturated fatty acids, induced the expression of cyclooxygenase-2 mediated through toll-like receptor 4. J. Biol. Chem. 276(20), 16683-16689 (2001).|4. Dietzen, D.J., Hastings, W.R., and Lublin, D.M. Caveolin is palmitoylated on multiple cysteine residues. Palmitoylation is not necessary for localization of caveolin to caveolae. J. Biol. Chem. 270(12), 6838-6842 (1995).|5. Robinson, L.J., and Michel, T. Mutagenesis of palmitoylation sites in endothelial nitric oxide synthase identifies a novel motif for dual acylation and subcellular targeting. Proc. Nat. Acad. Sci. USA 92(25), 11776-11780 (1995).|6. Topinka, J.R., and Bredt, D.S. N-terminal palmitoylation of PSD-95 regulates association with cell membranes and interaction with K+ channel Kv1.4. Neuron 20(1), 125-134 (1998).|7. Miggin, S.M., Lawler, O.A., and Kinsella, B.T. Palmitoylation of the human prostacyclin receptor. Functional implications of palmitoylation and isoprenylation. J. Biol. Chem. 278(9), 6947-6958 (2003).

Flumequine-13C3is intended for use as an internal standard for the quantification of flumequine by GC- or LC-MS. Flumequine is a fluoroquinolone antibiotic.1It is active againstS. aureus, S. pyogenes, B. subtilis, E. coli, P. aeruginosa, S. faecalis, andK. pneumoniae(MICs = 1-100 μg/ml). Flumequine is also active against field isolates of B. hyodysenteriae (MICs = 6.25-200 μg/ml).2It inhibits DNA gyrase, disrupting supercoiling of bacterial DNA to block transcription and replication.3In vivo, flumequine (50 mg/kg) increases survival in rat models ofP. vulgaris-induced urinary tract infection andP. mirabilis-induced prostatitis.1Formulations containing flumequine have been used in the treatment of urinary tract infections in veterinary medicine. 1.Rohlfing, S.R., Gerster, J.R., and Kvam, D.C.Bioevaluation of the antibacterial flumequine for urinary tract useAntimicrob. Agents Chemother.10(1)20-24(1976) 2.Aller-Morán, L.M., Martínez-Lobo, F.J., Rubio, P., et al.Evaluation of the in vitro activity of flumequine against field isolates of Brachyspira hyodysenteriaeRes. Vet. Sci.10351-53(2015) 3.Smith, J.T.The mode of action of 4-quinolones and possible mechanisms of resistanceJ. Antimicrob. Chemother.18 (Suppl. D)21-29(1986)

Nitisinone-13C6is intended for use as an internal standard for the quantification of nitisinone by GC- or LC-MS. Nitisinone is an inhibitor of 4-hydroxyphenylpyruvate dioxygenase (HPPD), which converts 4-hydroxyphenylpyruvate (HPPA) to homogentisate in the tyrosine catabolic pathway.1Nitisinone increases urinary levels of HPPA and 4-hydroxyphenyllactate (HPLA) in rats when administered at a dose of 10 mg/kg. Nitisinone (3 mg/kg) prevents the neonatal lethality of fumarylacetoacetate hydrolase (FAH) deficiency in mice when administered to pregnant dams.2It exhibits hepatoprotective effects inFAH-/-mice, such as prevention of increases in plasma levels of aspartate serine aminotransferase (AST) and conjugated bilirubin, when administration is continued following birth at a dose of 1 mg/kg. Nitisinone (100 μg) decreases urinary excretion of homogentisate and increases urinary excretion of HPPA, HPLA, and 4-hydroxyphenylacetate in a mouse model of alkaptonuria induced by ethylnitrosourea.3Formulations containing nitisinone have been used in the treatment of hereditary tyrosinemia type 1 (HT-1). 1.Ellis, M.K., Whitfield, A.C., Gowans, L.A., et al.Inhibition of 4-hydroxyphenylpyruvate dioxygenase by 2-(2-nitro-4-trifluoromethylbenzoyl)-cyclohexane-1,3-dione and 2-(2-chloro-4-methanesulfonylbenzoyl)-cyclohexane-1,3-dioneToxicol. Appl. Pharmacol.133(1)12-19(1995) 2.Grompe, M., Lindstedt, S., al-Dhalimy, M., et al.Pharmacological correction of neonatal lethal hepatic dysfunction in a murine model of hereditary tyrosinaemia type INat. Genet.10(4)453-460(1995) 3.Suzuki, Y., Oda, K., Yoshikawa, Y., et al.A novel therapeutic trial of homogentisic aciduria in a murine model of alkaptonuriaJ. Hum. Genet.44(2)79-84(1999)

5(6)-EET is a fully racemic version of the enantiomeric forms biosynthesized from arachidonic acid by cytochrome P450 enzymes. In solution, 5(6)-EET degrades into 5,6-DiHET and 5(6)-δ-lactone, which can be converted to 5(6)-DiHET and quantified by GC-MS. In neuroendocrine cells, such as the anterior pituitary and pancreatic islets, 5(6)-EET has been implicated in the mobilization of calcium and hormone secretion. 5(6)-EET is an inhibitor of T-type voltage-gated calcium channels (Cav3) that inhibits isoforms Cav3.1, Cav3.2 (IC50 = 0.54 μM), and Cav3.3 and decreases nifedipine-resistant phenylephrine-induced vasoconstriction in isolated mouse mesenteric arteries via Cav3.2 blockade when used at a concentration of 3 μM. In addition, it is a substrate of COX-1 and COX-2, as measured by oxygen consumption and product formation assays when used at a concentration of 50 μM. (±)5(6)-EET is provided as a mixture of the free acid and lactone.

L-Tyrosine-13C9,15N is intended for use as an internal standard for the quantification of L-tyrosine by GC- or LC-MS. L-Tyrosine is a non-essential amino acid.1It is produced by hydroxylation of phenylalanine by phenylalanine hydroxylase but can also be obtained from dietary sources or degradation of endogenous proteins, resulting in L-tyrosine release.1,2L-Tyrosine is a precursor in the biosynthesis of catecholamine neurotransmitters, melanins, and thyroid hormones.3Plasma, skeletal muscle, and erythrocyte levels of L-tyrosine are decreased in patients with chronic kidney disease.1 1.Kopple, J.D.Phenylalanine and tyrosine metabolism in chronic kidney failureJ. Nutr.137(6 Suppl 1)1586S-1590S(2007) 2.Webster, D., and Wildgoose, J.Tyrosine supplementation for phenylketonuriaCochrane DB Syst. Rev.2013(6)CD001507(2013) 3.Slominski, A., and Paus, R.Towards defining receptors for L-tyrosine and L-DOPAMol. Cell Endocrinol.99(2)C7-C11(1994)

Rhein-13C4 is intended for use as an internal standard for the quantification of rhein by GC- or LC-MS. Rhein is an anti-inflammatory anthraquinone found in rhubarb and is the bioactive derivative of its prodrug diacerein . At 10 μM, rhein inhibits IL-1β signaling, suppressing signaling through NF-κB, and reduces the expression of the matrix metalloproteases MMP-1 and MMP-13.1 It inhibits IKKβ (IC50 = 11.8 μM), decreasing iNOS and IL-6 expression in LPS-stimulated macrophages but paradoxically increasing TNF-α, IL-1β, and HMBG1 expression.2 Rhein shows efficacy against pancreatic fibrosis, chronic pancreatitis, and hyperglycemia-induced pancreatic β-cell apoptosis.3,4 It also inhibits angiogenesis of breast cancer cells under normoxic and hypoxic conditions.5

Nitrofurantoin-13C3is intended for use as an internal standard for the quantification of nitrofurantoin by GC- or LC-MS. Nitrofurantoin is a nitrofuran antibiotic.1In vivo, nitrofurantoin (25-100 mg/kg) reducesE. colireplication and abscess formation in the renal medulla of infected rats in a dose-dependent manner. It prevents kidney and bladder infection in rats following bladder inoculation with clinical isolates ofP. mirabilis. Nitrofurantoin also prevents alkalization of urine, as well as calculi and abscess formation, in a rat model ofP. vulgarisurinary tract infection.2Formulations containing nitrofurantoin have been used to treat urinary tract infections. 1.Rocha, H., Da Silva Teles, E., and Barros, M.Site of action of nitrofurantoin in experimental urinary tract infectionAppl. Microbiol.18(4)547-549(1969) 2.Hossack, D.J.N.Proteus vulgaris urinary tract infections in rats; treatment with nitrofuran derivativesBr. J. Pharmacol. Chemother.19(2)306-312(1962)

Olsalazine-13C6is intended for use as an internal standard for the quantification of olsalazine by GC- or LC-MS. Olsalazine is an orally bioavailable prodrug form of the anti-inflammatory agent 5-aminosalicylic acid that is cleaved by bacterial azo reductases in the gut to generate active 5-ASA.1In vitro, olsalazine increases ion transport in isolated rabbit distal ileum when applied to the luminal side (ED50= 0.3 mM) and stimulates fluid transport in rat jejunum when used at a concentration of 5 mM.2,3Olsalazine (150 mg/kg for 8 days) improves stool consistency and decreases occult and gross bleeding as well as myeloperoxidase (MPO) activity and leukotriene B4levels in colon tissue in a mouse model of acute colitis induced by dextran sulfate .4Olsalazine also inhibits bovine xanthine oxidasein vitro(IC50= 3.4 mg/L) and lowers serum uric acid levels in a mouse model of hyperuricemia induced by oxonic acid when administered at a dose of 20 mg/kg.5Formulations containing olsalazine have been used in the treatment of inflammatory bowel disease (IBD) and ulcerative colitis. 1.Nugent, S.G., Kumar, D., Rampton, D.S., et al.Intestinal luminal pH in inflammatory bowel disease: Possible determinants and implications for therapy with aminosalicylates and other drugsGut48(4)571-577(2001) 2.Pamukcu, R., Hanauer, S.B., and Chang, E.B.Effect of disodium azodisalicylate on electrolyte transport in rabbit ileum and colon in vitro. Comparison with sulfasalazine and 5-aminosalicylic acidGastroenterology95(4)975-981(1988) 3.Mohsen, A.Q.M., Mulvey, D., Priddle, J.D., et al.Effects of olsalazine in the jejunum of the ratGut28(3)346-352(1987) 4.Murthy, S., Murthy, N.S., Coppola, D., et al.The efficacy of BAY y 1015 in dextran sulfate model of mouse colitisInflamm. Res.46(6)224-233(1997) 5.Niu, Y., Li, H., Gao, L., et al.Old drug, new indication: Olsalazine sodium reduced serum uric acid levels in mice via inhibiting xanthine oxidoreductase activityJ. Pharmacol. Sci.135(3)114-120(2017)