lc-ms

MAK683 hydrochloride embryonic ectodermal development (EED) inhibitor, also a potent PRC2 inhibitor, blocked cancer cell proliferation (IC50=1.014nM), with IC50 values of 59, 26, and 89 nM measured in EED Alphascreen, ELISA, and LC-MS assays, respectively.

MAK683 is an inhibitor of embryonic ectoderm development (EED) (IC50s: 59, 89, 26 nM in EED Alphascreen binding, LC-MS and ELISA assay).

TAK-632, a potent pan-Raf inhibitor (GenScript, 2020), is characterized by its molecular weight [M] for [C 22 H 19 FN 2 O 2] of 362.4 by LC-MS, with a purity of 99% (HPLC). The compound exhibits white to off-white solid form and has a melting point [M] ranging from 178°C to 182°C (GenScript, 2020). Its solubility profile includes DMSO, in which it is soluble to 100mM (GenScript, 2020).

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)

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)

O-Des[2-aminoethyl]-O-carboxymethyl dehydroamlodipine is a major metabolite of the calcium channel inhibitor amlodipine .1 1.Taguchi, R., Naito, T., Sato, H., et al.Validated LC-MS/MS method for the simultaneous determination of amlodipine and its major metabolites in human plasma of hypertensive patientsTher. Drug Monit.39(6)625-631(2017)

D-Fructose-13C6 can be used as an internal standard for the quantification of D-fructose by GC- or LC-MS.

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

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

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).

N-desmethyl Rosuvastatin is an active metabolite of the HMG-CoA reductase inhibitor rosuvastatin .1,2N-desmethyl Rosuvastatin is formed when rosuvastatin undergoes demethylation, primarily by the cytochrome P450 (CYP) isoform CYP2C9 and to a lesser extent by CYP2C19 and CYP3A4.1 1.Macwan, J.S., Ionita, I.A., and Akhlaghi, F.A simple assay for the simultaneous determination of rosuvastatin acid, rosuvastatin-5S-lactone, and N-desmethyl rosuvastatin in human plasma using liquid chromatography-tandem mass spectrometry (LC-MS/MS)Anal. Bioanal. Chem.402(3)1217-1227(2012) 2.Bai, X., Wang, X.P., He, G.D., et al.Simultaneous determination of rosuvastatin, rosuvastatin-5 S-lactone, and N-desmethyl rosuvastatin in human plasma by UPLC-MS/MS and its application to clinical studyDrug Res. (Stuttg.)68(6)328-334(2018)

Gliotoxin-13C13is intended for use as an internal standard for the quantification of gliotoxin by GC- or LC-MS. Gliotoxin is an immunosuppressive mycotoxin produced by pathogenic strains ofAspergillusand other fungi with diverse biological activities.1,2,3,4,5,6,7,8It inhibits 20S proteasomal chymotrypsin activity (IC50= 10 μM), blocking the degradation of IκBα and preventing the activation of NF-κB.2,3Gliotoxin induces apoptosis in monocytes and dendritic cells and reduces phagocytosis by neutrophils.4,5It suppresses viral infection by Nipah and Hendra virus in HEK293T cells (IC50s = 149 and 579 nM, respectively).6Under reducing conditions, gliotoxin inhibits leukotriene A4hydrolase epoxide hydrolase activity, but not aminopeptidase activity, and leukotriene B4synthesis in neutrophils and monocytes.7

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

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

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)

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.

13C C16 Sphingomyelin is an isotopically enriched form of C16 sphingomyelin with carbon-13 occurring on the fatty acid portion. It is intended for use as an internal standard for the quantification of C16 sphingomyelin by GC- or LC-MS. C16 Sphingomyelin is a form of sphingomyelin containing palmitate (16:0) at the variable acylation position. It is the most common form of sphingomyelin found in eggs and is less abundant in the brain and in milk. C16 Sphingomyelin interacts with cholesterol in ordered lipid domains (lipid rafts). Sphingomyelinases remove phosphorylcholine from C16 sphingomyelin to produce C16 ceramide. While ceramides commonly induce apoptosis, ceramides with different fatty acid chain lengths might direct distinct functions and, in some cases, reduce apoptosis.