Carbon-13 Labeled Compounds

D-Glucose-13C6 (Dextrose-13C6) is an isotopic marker of D-Glucose, which can be used as a metabolic tracer for the study of metabolism-related diseases and metabolic processes of some substances in the body.

5-Fluorouracil-13C,15N2 is intended for use as an internal standard for the quantification of 5-flurouracil by GC- or LC-MS. 5-Fluorouracil is a pyrimidine analog that irreversibly inhibits thymidylate synthase, blocking the synthesis of thymidine which is required for DNA synthesis. Intracellular metabolites of 5-fluorouracil exert cytotoxic effects by either inhibiting thymidylate synthetase, or through incorporation into RNA and DNA, ultimately initiating apoptosis.

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)

Erlotinib-13C6 (CP-358774-13C6) is a 13C-labeled Erlotinib. Erlotinib is a directly acting EGFR tyrosine kinase inhibitor, with an IC50 of 2 nM for human EGFR[1]. Erlotinib reduces EGFR autophosphorylation in intact tumor cells with an IC50 of 20 nM. Erlotinib is used for the treatment of non-small cell lung cancer[1].Stable heavy isotopes of hydrogen, carbon, and other elements have been incorporated into drug molecules, largely as tracers for quantitation during the drug development process[2]. [1]. Moyer JD, et al. Induction of apoptosis and cell cycle arrest by CP-358,774, an inhibitor of epidermal growth factor receptor tyrosine kinase. Cancer Res. 1997, 57(21), 4838-4848.[2]. Russak EM, et al. Impact of Deuterium Substitution on the Pharmacokinetics of Pharmaceuticals. Ann Pharmacother. 2019;53(2):211-216.

4-Trifluoromethylsalicylic acid-13C6 is 13C-labeled 4-Trifluoromethylsalicylic acid, mainly used as a quantitative tracer in drug development. 4-Trifluoromethylsalicylic acid is also a platelet aggregation inhibitor.

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)

L-Lactic acid-13C3 is a stable isotope labeled L-Lactic acid analog. L-Lactic acid-13C3 can be used for lactate metabolism research.

1,2,3-Trioctanoyl-rac-glycerol-13C3 is intended for use as an internal standard for the quantification of 1,2,3-trioctanoyl-rac-glycerol by GC- or LC-MS. 1,2,3-Trioctanoyl-rac-glycerol is a triacylglycerol that contains octanoic acid at the sn-1, sn-2, and sn-3 positions. Dietary administration of 1,2,3-trioctanoyl-rac-glycerol increases hippocampal levels of the glycolytic metabolites glucose 6-phosphate, fructose 6-phosphate, and β-hydroxybutyrate and the seizure threshold in the 6 Hz psychomotor seizure test in mice.1 Formulations containing 1,2,3-trioctanoyl-rac-glycerol have been used in cosmetic products as thickening and skin-conditioning agents.

Phenol-13C6is a building block.1It has been used in the synthesis of13C6-labeled metabolites of (±)-asenapine . 1.Kuethe, J.T.Synthesis of stable isotope‐labeled metabolites of asenapineJ. Labelled Comp. Radiopharm.55(5)180-185(2012)

Rafoxanide 13C6 is a labeled Rafoxanide . Rafoxanide is a salicylanilide used as an antiparasitic agent.

Zonisamide-13C2,15N is intended for use as an internal standard for the quantification of zonisamide by GC- or LC-MS. Zonisamide is an antiepileptic agent.1 It selectively inhibits the repeated firing of sodium channels (IC50 = 2 μg/ml) in mouse embryo spinal cord neurons and inhibits spontaneous channel firing when used at concentrations greater than 10 μg/ml.2 In rat cerebral cortex neurons, zonisamide (1-1,000 μM) inhibits T-type calcium channels with a maximum reduction of 60% of the calcium current.3 Zonisamide inhibits H. pylori recombinant carbonic anhydrase (CA) and the human CA isoforms I, II, and V with Ki values of 218, 56, 35, and 21 nM, respectively.4,5 In mice, it has anticonvulsant activity against maximal electroshock seizure (MES) and pentylenetetrazole-induced maximal, but not minimal, seizures (ED50s = 19.6, 9.3, and >500 mg/kg, respectively). Zonisamide (40 mg/kg, p.o.) prevents MPTP-induced decreases in the levels of dopamine , but not homovanillic acid or dihydroxyphenyl acetic acid , and increases MPTP-induced decreases in the dopamine turnover rate in mouse striatum in a model of Parkinson's disease.6 Formulations containing zonisamide have been used in the treatment of partial seizures in adults with epilepsy. |1. Masuda, Y., Ishizaki, M., and Shimizu, M. Zonisamide: Pharmacology and clinical efficacy in epilepsy. CNS Drug Rev. 4(4), 341-360 (1998).|2. Rock, D.M., Macdonald, R.L., and Taylor, C.P. Blockade of sustained repetitive action potentials in cultured spinal cord neurons by zonisamide (AD 810, CI 912), a novel anticonvulsant. Epilepsy Res. 3(2), 138-143 (1989).|3. Suzuki, S., Kawakami, K., Nishimura, S., et al. Zonisamide blocks T-type calcium channel in cultured neurons of rat cerebral cortex. Epilepsy Res. 12(1), 21-27 (1992).|4. Nishimori, I., Vullo, D., Minakuchi, T., et al. Carbonic anhydrase inhibitors: Cloning and sulfonamide inhibition studies of a carboxyterminal truncated α-carbonic anhydrase from Helicobacter pylori. Bioorg. Med. Chem. Lett. 16(8), 2182-2188 (2006).|5. De Simone, G., Di Fiore, A., Menchise, V., et al. Carbonic anhydrase inhibitors. Zonisamide is an effective inhibitor of the cytosolic isozyme II and mitochondrial isozyme V: Solution and X-ray crystallographic studies. Bioorg. Med. Chem. Lett. 15(9), 2315-2320 (2005).|6. Yabe, H., Choudhury, M.E., Kubo, M., et al. Zonisamide increases dopamine turnover in the striatum of mice and common marmosets treated with MPTP. J. Pharmacol. Sci. 110(1), 64-68 (2009).

Caffeic acid-13C3 is an isotopically enriched form of caffeic acid that is intended for use as an internal standard for the quantification of caffeic acid by GC- or LC-MS. Caffeic acid is an inhibitor of 5-LO , with IC50 values of 3.7-72 μM, and 12-LO, with IC50 values of 5.1-30 μM.

Lamivudine 13C,15N2, an impurity of Lamivudine (BCH-189), functions as an inhibitor of both HIV-1/2 reverse transcriptase and hepatitis B virus reverse transcriptase, classifying it as a nucleoside reverse transcriptase inhibitor (NRTIs).

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)

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)

Ochratoxin A-13C20is intended for use as an internal standard for the quantification of ochratoxin A by GC- or LC-MS. Ochratoxin A is a mycotoxin that has been found inAspergillusandPenicillium.1It increases lipid peroxide levels and the number of apoptotic cells, as well as reduces superoxide dismutase activity in rat kidney when administered at a dose of 120 μg/kg.2Topical application of ochratoxin A (80 μg/mouse) induces DNA damage, cell cycle arrest at the G0/G1phase, and apoptosis in mouse skin cells.1It also initiates tumor formation in a two-stage mouse skin tumorigenesis model. Ochratoxin A has been found as a contaminant in a variety of foods.3

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)

L-Thyroxine-13C9,15N is intended for use as an internal standard for the quantification of L-thyroxine by GC- or LC-MS. L-Thyroxine is a synthetic form of the thyroid hormone thyroxine. In vivo, L-thyroxine (0.9 and 2.7 μg) inhibits synthesis and release of thyrotropin induced by thyrotropin-releasing hormone from the anterior pituitary in mice. It also reverses decreases in levels of circulating thymic serum factor (FTS) and the number of T rosette-forming cells in an old age-induced mouse model of hypothyroidism. Formulations containing L-thyroxine have been used in the treatment of hypothyroidism.

(E/Z)-Eltrombopag 13C4 ((E/Z)-SB-497115 13C4) is a mixture complex of E-Eltrombopag and Z-Eltrombopag, with 13C labeled. Z-Eltrombopag is a thrombopoietin (TPO) receptor agonist developed for certain conditions that lead to thrombocytopenia.

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)

Ribavirin-13C5is intended for use as an internal standard for the quantification of ribavirin by GC- or LC-MS. Ribavirin is an antiviral guanosine nucleoside analog.1,2Upon entry into cells, ribavirin is metabolized to an active triphosphate form that induces viral RNA chain termination and inhibits viral polymerases. It reduces replication in a panel of seven RNA and four DNA viruses in Vero cells (EC50s = 2-95 μg/ml).3Ribavirin also reduces replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Vero cells (EC50= 109.5 μM).4Aerosol administration of ribavirin (30 mg/kg) reduces mortality in a mouse model of influenza A infection.5Formulations containing ribavirin have been used in the treatment of respiratory syncytial virus (RSV), hepatitis C virus (HCV), and viral hemorrhagic fevers. 1.Gilbert, B.E., and Knight, V.Biochemistry and clinical applications of ribavirinAntimicrob. Agents Chemother.30(2)201-205(1986) 2.Gordon, C.J., Tchesnokov, E.P., Woolner, E., et al.Remdesivir is a direct-acting antiviral that inhibits RNA-dependent RNA polymerase from severe acute respiratory syndrome coronavirus 2 with high potencyJ. Biol. Chem.295(20)6785-6797(2020) 3.Kirsi, J.J., North, J.A., McKernan, P.A., et al.Broad-spectrum antiviral activity of 2-β-D-ribofuranosylselenazole-4-carboxamide, a new antiviral agentAntimicrob. Agents Chemother.24(3)353-361(1983) 4.Wang, M., Cao, R., Zhang, L., et al.Remdesivir and chloroquine effectively inhibit the recently emerged novel coronavirus (2019-nCoV) in vitroCell Res.30(3)269-271(2020) 5.Wilson, S.Z., Knight, V., Wyde, P.R., et al.Amantadine and ribavirin aerosol treatment of influenza A and B infection in miceAntimicrob. Agents Chemother.17(4)642-648(1980)

Lauric acid-13C is intended for use as an internal standard for the quantification of lauric acid by GC- or LC-MS. Lauric acid is a medium-chain saturated fatty acid. It has been found at high levels in coconut oil.1Lauric acid induces the activation of NF-κB and the expression of COX-2, inducible nitric oxide synthase (iNOS), and IL-1α in RAW 264.7 cells when used at a concentration of 25 μM.2

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)

1,2-Dipalmitoyl-13C-sn-glycero-3-PC is intended for use as an internal standard for the quantification of 1,2-dipalmitoyl-sn-glycero-3-PC by GC- or LC-MS. 1,2-Dipalmitoyl-sn-glycero-3-PC (DPPC) is a zwitterionic glycerophospholipid commonly used in the formation of lipid monolayers, bilayers, and liposomes for use in a variety of applications.1,2,3,4 It has been used in the formation of proteoliposomes for implantation of γ-glutamyl transpeptidase into human erythrocyte membranes.3 Incorporation of glycosphingolipid antigens into DPPC-containing liposomes increases the immunogenicity of the antigens in mice.4 |1. Ege, C., and Lee, K.Y.C. Insertion of Alzheimer's Aβ40 peptide into lipid monolayers. Biophys. J. 87(3), 1732-1740 (2004).|2. Leekumjorn, S., and Sum, A.K. Molecular simulation study of structural and dynamic properties of mixed DPPC/DPPE bilayers. Biophys. J. 90(11), 3951-3965 (2006).|3. Kalra, V.K., Sikka, S.C., and Sethi, G.S. Transport of amino acids in γ-glutamyl transpeptidase-implanted human erythrocytes. J. Biol. Chem. 256(11), 5567-5571 (1981).|4. Uemura, A., Watarai, S., Iwasaki, T., et al. Induction of immune responses against glycosphingolipid antigens: Comparison of antibody responses in mice immunized with antigen associated with liposomes prepared from various phospholipids. J. Vet. Med. Sci. 67(12), 1197-1201 (2005).

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)

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

Zanamivir-13C,15N2is intended for use as an internal standard for the quantification of zanamivir by GC- or LC-MS. Zanamivir is a sialic acid analog that inhibits neuraminidase release of newly replicated influenza virus particles.1It has been shown to selectively inhibit the growth of influenza A and B viruses in plaque reduction assays with IC50values ranging from 5 to 14 nM and to directly inhibit influenza A and B virus neuraminidases with IC50values ranging from 0.6 to 7.9 nMin vitro. Intranasal zanamivir administration at 0.4 mg/kg twice daily reduces mortality and viral titers in lung homogenates of mice infected with influenza. 1.Elliott, M.Zanamivir: From drug design to the clinicPhilos. Trans. R. Soc. Lond. B Biol Sci.356(1416)1885-1893(2001)

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)

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)

Zearalenone-13C18is intended for use as an internal standard for the quantification of zearalenone by GC- or LC-MS. Zearalenone is a mycotoxin that has been found inFusariumand has estrogenic activities.1It binds to human estrogen receptor α (ERα) and ERβ (IC50s = 9 and 5.8 nM, respectively).2Zearalenone induces precocious development of mammary tissues in young female pigs and prepucial enlargement in young male pigs.3Zearalenone (1.5-5 mg/kg of diet) induces hyperestrogenism in pigs. It also induces degeneration of meiotic chromatin in oocytes and reduces fertility in pigs when administered at a dose of 200 μg/kg.4Zearalenone has been found as a contaminant in wheat, maize, and barley and livestock feeds.3,4

Dichlorphenamide-13C6is intended for use as an internal standard for the quantification of dichlorphenamide by GC- or LC-MS. Dichlorphenamide is a sulfonamide and an orally bioavailable carbonic anhydrase (CA) inhibitor (Kis = 1.20, 38, 50, and 50 nM for the human CA isoforms CAI, CAII, CAIX, and CAXII, respectively).1It lowers intraocular pressure in rabbits when 50 μl of a 10% solution is applied topically to the eye.2Dichlorphenamide rescues the potassium deficiency and prevents insulin-induced paralysis in a rat model of familial hypokalemic periodic paralysis when administered at a dose of 5.6 mg/kg per day for ten days.3Formulations containing dichlorphenamide have been used in the treatment of glaucoma and primary periodic paralysis.

Cefazolin-13C2,15N is intended for use as an internal standard for the quantification of cefazolin by GC- or LC-MS. Cefazolin is a broad-spectrum cephalosporin antibiotic that is active in vitro against various Gram-positive and Gram-negative bacteria (MICs = 0.2-12.5 μg/ml). It also inhibits the growth of clinical isolates of S. aureus, E. coli, P. mirabilis, and K. pneumoniae (MICs = 0.1-25 μg/ml). In vivo, cefazolin protects against S. aureus, E. coli, and P. mirabilis infection in mice (ED50s = <0.09-1.78, 0.44-3.63, and 2.31-5.2 mg/animal, respectively). Formulations containing cefazolin have been used to treat a variety of bacterial infections.

2-Nitrobenzaldehyde semicarbazone (13C, 15N2) is utilized in the LC-MS/MS method for semicarbazide analysis.

1,2-Dioleoyl-rac-glycerol-13C3 is intended for use as an internal standard for the quantification of 1,2-dioleoyl-rac-glycerol by GC- or LC-MS. 1,2-dioleoyl-rac-glycerol is a diacylglycerol that contains oleic acid at the sn-1 and sn-2 positions. It effectively binds the C1 domain to activate conventional protein kinase C forms and serves as a substrate for diacylglycerol kinases and multisubstrate lipid kinase.1,2,3 |1. Yamaguchi, Y., Shirai, Y., Matsubara, T., et al. Phosphorylation and up-regulation of diacylglycerol kinase γ via its interaction with protein kinase Cγ. J. Biol. Chem. 281(42), 31627-31637 (2006).|2. Zhou, Q.Z., Raynor, R.L., Wood, M.G., Jr., et al. Structure-activity relationship of synthetic branched-chain distearoylglycerol (distearin) as protein kinase C activators. Biochemistry 27(19), 7361-7365 (1988).|3. Epand, R.M., Shulga, Y.V., Timmons, H.C., et al. Substrate chirality and specificity of diacylglycerol kinases and the multisubstrate lipid kinase. Biochemistry 46(49), 14225-14231 (2007).

Sofosbuvir-13C-d3 is the 13C and deuterated compound of Sofosbuvir. Sofosbuvir has a CAS number of 1190307-88-0. Sofosbuvir is a uridine monophosphate analog inhibitor of hepatitis C virus (HCV) polymerase NS5B that is used as an antiviral agent in the treatment of chronic hepatitis C.

Roxadustat-13C-15N is 13C and 15N labeled Roxadustat.

Taltirelin-13C-d3 is the 13C and deuterated compound of Taltirelin. Taltirelin has a CAS number of 103300-74-9. Taltirelin is at thyrotropin-releasing hormone receptor (TRH-R) superagonist (IC50 of 910 nM and EC50 of 36 nM for stimulating an increase in cytosolic Ca2+ concentration (Ca2+ release))[1].

13C-d3-AOH1996 is the 13C and deuterated compound of AOH1996. 13C-AOH1996 has a CAS number of 2089314-64-5. AOH1996 is an orally active ligand for the replicasome component PCNA (proliferating cell nuclear antigen), targeting the transcription-replication conflict (TRC).AOH1996 interferes with the interaction of PCNA with its binding proteins, leading to DNA replication stress and apoptosis.AOH1996 causes proteasome-dependent rpb1 degradation and lethal DNA damage by stabilizing the interaction between PCNA and RNA polymerase II.AOH1996 acts synergistically with DNA damaging agents to inhibit tumor cell growth. AOH1996 inhibits tumor cell growth by stabilizing the interaction between PCNA and RNA polymerase II, leading to proteasome-dependent rpb1 degradation and lethal DNA damage.AOH1996 acts synergistically with DNA damaging agents.

Vadadustat-13C2-15N is 13C and 15N labeled Vadadustat. Vadadustat has a CAS number of 1000025-07-9. Vadadustat is a novel, titratable, oral hypoxia-inducible factor prolyl hydroxylase (HIF-PH) inhibitor in development for the treatment of anemia.

Riociguat-13C-d6 is the 13C and deuterated compound of Riociguat. Riociguat has a CAS number of 625115-55-1. Riociguat is a stimulator of guanylate cyclase which causes relaxation of vascular smooth muscle and is used to treat severe pulmonary arterial hypertension.

Cyanuric acid-13C3 is 13C labeled Cyanuric acid.

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

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).

L-Leucine-1-13C (L-Leucine-13C) is a 13C-labeled L-Leucine that significantly enhances the affinity of GLP-4.

Benzophenone-13C (carbonyl-13C) is the 13C labeled compound of Benzophenone. Benzophenone has a CAS number of 119-61-9.

2,4-Dichlorophenol-13C6 the 13C and deuterated compound of 2,4-Dichlorophenol. 2,4-Dichlorophenol has a CAS number of 120-83-2. 2,4-Dichlorophenol is the precursor to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D).

Lercanidipine-13C-d3 HCl the 13C and deuterated compound of Lercanidipine HCl. Lercanidipine HCl has a CAS number of 132866-11-6. Lercanidipine is a calcium channel blocker of the dihydropyridine class.

5-Hydroxy Saxagliptin-13C-d2 HCl the 13C and deuterated compound of 5-Hydroxy Saxagliptin HCl. 5-Hydroxy Saxagliptin HCl has a CAS number of 841302-24-7.

3,3',5-Triiodothyronine-(tyrosine ring-13C6) is the 13C labeled compound of 3,3',5-Triiodothyronine. 3,3',5-Triiodothyronine has a CAS number of 5817-39-0.