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Record Information
StatusDetected and Quantified
Creation Date2005-11-16 15:48:42 UTC
Update Date2021-04-12 19:31:26 UTC
Secondary Accession Numbers
  • HMDB0002083
  • HMDB0062556
  • HMDB0062606
  • HMDB00736
  • HMDB02083
  • HMDB62556
  • HMDB62606
Metabolite Identification
Common NameIsobutyryl-L-carnitine
DescriptionIsobutyryl-L-carnitine is an acylcarnitine. More specifically, it is an isobutyric acid ester of carnitine. Acylcarnitines were first discovered more than 70 year ago (PMID: 13825279 ). It is believed that there are more than 1000 types of acylcarnitines in the human body. The general role of acylcarnitines is to transport acyl-groups (organic acids and fatty acids) from the cytoplasm into the mitochondria so that they can be broken down to produce energy.  This process is known as beta-oxidation. According to a recent review [Dambrova et al. 2021, Physiological Reviews], acylcarnitines (ACs) can be classified into 9 different categories depending on the type and size of their acyl-group: 1) short-chain ACs; 2) medium-chain ACs; 3) long-chain ACs; 4) very long-chain ACs; 5) hydroxy ACs; 6) branched chain ACs; 7) unsaturated ACs; 8) dicarboxylic ACs and 9) miscellaneous ACs. Short-chain ACs have acyl-groups with two to five carbons (C2-C5), medium-chain ACs have acyl-groups with six to thirteen carbons (C6-C13), long-chain ACs have acyl-groups with fourteen to twenty once carbons (C14-C21) and very long-chain ACs have acyl groups with more than 22 carbons. Isobutyryl-L-carnitine is therefore classified as a short chain AC. As a short-chain acylcarnitine isobutyryl-L-carnitine is a member of the most abundant group of carnitines in the body, comprising more than 50% of all acylcarnitines quantified in tissues and biofluids (PMID: 31920980 ). Some short-chain carnitines have been studied as supplements or treatments for a number of diseases, including neurological disorders and inborn errors of metabolism. In particular isobutyryl-L-carnitine is elevated in the blood or plasma of individuals with isobutyryl-coa dehydrogenase deficiency (PMID: 20591710 ), glutaric aciduria type 2 (PMID: 20591710 ), ethylmalonic encephalopathy (PMID: 20591710 ), and gestational diabetes mellitus (PMID: 29626588 ). It is also decreased in the blood or plasma of individuals with traumatic brain injury (PMID: 23560894 ). Isobutyryl-L-carnitine is elevated in the urine of individuals with glutaric aciduria type 2 (PMID: 2288224 ), multiple acyl-CoA dehydrogenation deficiency (PMID: 3383426 ), and acute coronary syndrome (PMID: 30316136 ). Carnitine acetyltransferase (CrAT, EC: is responsible for the synthesis of all short-chain and short branched-chain acylcarnitines (PMID: 23485643 ). The study of acylcarnitines is an active area of research and it is likely that many novel acylcarnitines will be discovered in the coming years. It is also likely that many novel roles in health and disease will be uncovered. An excellent review of the current state of knowledge for acylcarnitines is available at [Dambrova et al. 2021, Physiological Reviews].
Isobutyryl-L-carnitineHMDB, ChEBI
Chemical FormulaC11H22NO4
Average Molecular Weight232.299
Monoisotopic Molecular Weight232.154334613
IUPAC Name(3R)-3-[(2-methylpropanoyl)oxy]-4-(trimethylazaniumyl)butanoate
Traditional Name(3R)-3-[(2-methylpropanoyl)oxy]-4-(trimethylammonio)butanoate
CAS Registry Number25518-49-4
InChI Identifier
Chemical Taxonomy
Description belongs to the class of organic compounds known as acyl carnitines. These are organic compounds containing a fatty acid with the carboxylic acid attached to carnitine through an ester bond.
KingdomOrganic compounds
Super ClassLipids and lipid-like molecules
ClassFatty Acyls
Sub ClassFatty acid esters
Direct ParentAcyl carnitines
Alternative Parents
  • Acyl-carnitine
  • Branched fatty acid
  • Dicarboxylic acid or derivatives
  • Tetraalkylammonium salt
  • Quaternary ammonium salt
  • Carboxylic acid ester
  • Carboxylic acid salt
  • Carboxylic acid derivative
  • Carboxylic acid
  • Organonitrogen compound
  • Hydrocarbon derivative
  • Organic oxide
  • Organopnictogen compound
  • Organic nitrogen compound
  • Carbonyl group
  • Organic oxygen compound
  • Amine
  • Organooxygen compound
  • Organic salt
  • Aliphatic acyclic compound
Molecular FrameworkAliphatic acyclic compounds
External Descriptors
Physiological effect

Health effect:


Route of exposure:


Biological location:


Naturally occurring process:


Industrial application:

Biological role:

Physical Properties
Experimental Properties
Melting PointNot AvailableNot Available
Boiling PointNot AvailableNot Available
Water SolubilityNot AvailableNot Available
LogPNot AvailableNot Available
Predicted Properties
Water Solubility0.058 g/LALOGPS
pKa (Strongest Acidic)4.27ChemAxon
pKa (Strongest Basic)-7.1ChemAxon
Physiological Charge0ChemAxon
Hydrogen Acceptor Count3ChemAxon
Hydrogen Donor Count0ChemAxon
Polar Surface Area66.43 ŲChemAxon
Rotatable Bond Count7ChemAxon
Refractivity81.84 m³·mol⁻¹ChemAxon
Polarizability24.64 ųChemAxon
Number of Rings0ChemAxon
Rule of FiveYesChemAxon
Ghose FilterNoChemAxon
Veber's RuleNoChemAxon
MDDR-like RuleNoChemAxon
Spectrum TypeDescriptionSplash KeyView
LC-MS/MSLC-MS/MS Spectrum - Quattro_QQQ 10V, Positive (Annotated)splash10-001i-5290000000-baab610a0cdc91406addSpectrum
LC-MS/MSLC-MS/MS Spectrum - Quattro_QQQ 25V, Positive (Annotated)splash10-001i-9000000000-8d180efb75e39baa17aaSpectrum
LC-MS/MSLC-MS/MS Spectrum - Quattro_QQQ 40V, Positive (Annotated)splash10-001i-9000000000-6311075865704b40d294Spectrum
1D NMR1H NMR SpectrumNot AvailableSpectrum
2D NMR[1H,13C] 2D NMR SpectrumNot AvailableSpectrum
Biological Properties
Cellular Locations
  • Extracellular
  • Membrane
Biospecimen Locations
  • Blood
  • Urine
Tissue Locations
  • Placenta
Normal Concentrations
BloodDetected and Quantified0.069 (0.015-0.203) uMChildren (1 - 13 years old)BothNormal details
BloodDetected but not QuantifiedNot QuantifiedAdult (>18 years old)BothNormal details
BloodDetected and Quantified0.069 (0.015-0.203) uMChildren (1-13 years old)BothNormal details
UrineDetected and Quantified0 umol/mmol creatinineInfant (0-1 year old)BothNormal details
UrineDetected and Quantified0.05-0.33 umol/mmol creatinineNewborn (0-30 days old)BothNormal
    • López Hernández Y...
UrineDetected and Quantified0.11 +/- 0.06 umol/mmol creatinineNewborn (0-30 days old)FemaleNormal
    • López Hernández Y...
UrineDetected and Quantified0.13 +/- 0.07 umol/mmol creatinineNewborn (0-30 days old)MaleNormal
    • López Hernández Y...
UrineDetected but not QuantifiedNot QuantifiedAdult (>18 years old)BothNormal details
Abnormal Concentrations
BloodDetected and Quantified0.034 (0.009-0.084) uMAdult (>18 years old)BothVery long-chain acyl-CoA dehydrogenase deficiency (vLCAD) details
UrineDetected and Quantified0 umol/mmol creatinineInfant (0-1 year old)Both
Short chain acyl-CoA dehydrogenase deficiency (SCAD)
Associated Disorders and Diseases
Disease References
Very Long Chain Acyl-CoA Dehydrogenase Deficiency
  1. Costa CG, Struys EA, Bootsma A, ten Brink HJ, Dorland L, Tavares de Almeida I, Duran M, Jakobs C: Quantitative analysis of plasma acylcarnitines using gas chromatography chemical ionization mass fragmentography. J Lipid Res. 1997 Jan;38(1):173-82. [PubMed:9034211 ]
Short Chain Acyl-Coa Dehydrogenase Deficiency
  1. Bhala A, Willi SM, Rinaldo P, Bennett MJ, Schmidt-Sommerfeld E, Hale DE: Clinical and biochemical characterization of short-chain acyl-coenzyme A dehydrogenase deficiency. J Pediatr. 1995 Jun;126(6):910-5. [PubMed:7776094 ]
Associated OMIM IDs
  • 201475 (Very Long Chain Acyl-CoA Dehydrogenase Deficiency)
DrugBank IDNot Available
Phenol Explorer Compound IDNot Available
FooDB IDFDB022213
KNApSAcK IDNot Available
Chemspider ID147286
KEGG Compound IDNot Available
BioCyc IDNot Available
BiGG IDNot Available
Wikipedia LinkNot Available
PubChem Compound168379
PDB IDNot Available
ChEBI ID84838
Food Biomarker OntologyNot Available
VMH IDNot Available
MarkerDB IDMDB00000241
Synthesis ReferenceStrack, Erich; Mueller, Detlef M. Preparation of O-acylcarnitines. Hoppe-Seyler's Zeitschrift fuer Physiologische Chemie (1970), 351(1), 95-8.
Material Safety Data Sheet (MSDS)Not Available
General References
  1. Sugiyama N, Kidouchi K, Kobayashi M, Wada Y: Carnitine deficiency in inherited organic acid disorders and Reye syndrome. Acta Paediatr Jpn. 1990 Aug;32(4):410-6. [PubMed:2288224 ]
  2. Kidouchi K, Niwa T, Nohara D, Asai K, Sugiyama N, Morishita H, Kobayashi M, Wada Y: Urinary acylcarnitines in a patient with neonatal multiple acyl-CoA dehydrogenation deficiency, quantified by a carboxylic acid analyzer with a reversed-phase column. Clin Chim Acta. 1988 Apr 29;173(3):263-72. [PubMed:3383426 ]
  3. Koeberl DD, Young SP, Gregersen NS, Vockley J, Smith WE, Benjamin DK Jr, An Y, Weavil SD, Chaing SH, Bali D, McDonald MT, Kishnani PS, Chen YT, Millington DS: Rare disorders of metabolism with elevated butyryl- and isobutyryl-carnitine detected by tandem mass spectrometry newborn screening. Pediatr Res. 2003 Aug;54(2):219-23. Epub 2003 May 7. [PubMed:12736383 ]
  4. Sass JO, Sander S, Zschocke J: Isobutyryl-CoA dehydrogenase deficiency: isobutyrylglycinuria and ACAD8 gene mutations in two infants. J Inherit Metab Dis. 2004;27(6):741-5. [PubMed:15505379 ]
  5. Minkler PE, Ingalls ST, Hoppel CL: High-performance liquid chromatographic separation of acylcarnitines following derivatization with 4'-bromophenacyl trifluoromethanesulfonate. Anal Biochem. 1990 Feb 15;185(1):29-35. [PubMed:2344045 ]
  6. Fontaine M, Briand G, Largilliere C, Degand P, Divry P, Vianey-Saban C, Mousson B, Vamecq J: Metabolic studies in a patient with severe carnitine palmitoyltransferase type II deficiency. Clin Chim Acta. 1998 May 25;273(2):161-70. [PubMed:9657346 ]
  7. Roe CR, Cederbaum SD, Roe DS, Mardach R, Galindo A, Sweetman L: Isolated isobutyryl-CoA dehydrogenase deficiency: an unrecognized defect in human valine metabolism. Mol Genet Metab. 1998 Dec;65(4):264-71. [PubMed:9889013 ]
  8. Sakuma T, Sugiyama N, Ichiki T, Kobayashi M, Wada Y, Nohara D: Analysis of acylcarnitines in maternal urine for prenatal diagnosis of glutaric aciduria type 2. Prenat Diagn. 1991 Feb;11(2):77-82. [PubMed:2062823 ]
  9. Matsumoto K, Takahashi M, Takiyama N, Misaki H, Matsuo N, Murano S, Yuki H: Enzyme reactor for urinary acylcarnitines assay by reversed-phase high-performance liquid chromatography. Clin Chim Acta. 1993 Jul 16;216(1-2):135-43. [PubMed:8222264 ]
  10. Vallee L, Fontaine M, Nuyts JP, Ricart G, Krivosic I, Divry P, Vianey-Saban C, Lhermitte M, Vamecq J: Stroke, hemiparesis and deficient mitochondrial beta-oxidation. Eur J Pediatr. 1994 Aug;153(8):598-603. [PubMed:7957409 ]
  11. Shalev DP, Soffer Y, Lewin LM: Investigations on the motility of human spermatozoa in a defined medium in the presence of metabolic inhibitors and of carnitine. Andrologia. 1986 Jul-Aug;18(4):368-75. [PubMed:3752540 ]
  12. Fontaine M, Briand G, Ser N, Armelin I, Rolland MO, Degand P, Vamecq J: Metabolic studies in twin brothers with 2-methylacetoacetyl-CoA thiolase deficiency. Clin Chim Acta. 1996 Nov 15;255(1):67-83. [PubMed:8930414 ]
  13. Simons K, Toomre D: Lipid rafts and signal transduction. Nat Rev Mol Cell Biol. 2000 Oct;1(1):31-9. [PubMed:11413487 ]
  14. Watson AD: Thematic review series: systems biology approaches to metabolic and cardiovascular disorders. Lipidomics: a global approach to lipid analysis in biological systems. J Lipid Res. 2006 Oct;47(10):2101-11. Epub 2006 Aug 10. [PubMed:16902246 ]
  15. Sethi JK, Vidal-Puig AJ: Thematic review series: adipocyte biology. Adipose tissue function and plasticity orchestrate nutritional adaptation. J Lipid Res. 2007 Jun;48(6):1253-62. Epub 2007 Mar 20. [PubMed:17374880 ]
  16. Lingwood D, Simons K: Lipid rafts as a membrane-organizing principle. Science. 2010 Jan 1;327(5961):46-50. doi: 10.1126/science.1174621. [PubMed:20044567 ]
  17. Violante S, Ijlst L, Ruiter J, Koster J, van Lenthe H, Duran M, de Almeida IT, Wanders RJ, Houten SM, Ventura FV: Substrate specificity of human carnitine acetyltransferase: Implications for fatty acid and branched-chain amino acid metabolism. Biochim Biophys Acta. 2013 Jun;1832(6):773-9. doi: 10.1016/j.bbadis.2013.02.012. Epub 2013 Feb 24. [PubMed:23485643 ]
  18. Elshenawy S, Pinney SE, Stuart T, Doulias PT, Zura G, Parry S, Elovitz MA, Bennett MJ, Bansal A, Strauss JF 3rd, Ischiropoulos H, Simmons RA: The Metabolomic Signature of the Placenta in Spontaneous Preterm Birth. Int J Mol Sci. 2020 Feb 4;21(3). pii: ijms21031043. doi: 10.3390/ijms21031043. [PubMed:32033212 ]
  19. FRITZ IB: Action of carnitine on long chain fatty acid oxidation by liver. Am J Physiol. 1959 Aug;197:297-304. doi: 10.1152/ajplegacy.1959.197.2.297. [PubMed:13825279 ]
  20. Makarova E, Makrecka-Kuka M, Vilks K, Volska K, Sevostjanovs E, Grinberga S, Zarkova-Malkova O, Dambrova M, Liepinsh E: Decreases in Circulating Concentrations of Long-Chain Acylcarnitines and Free Fatty Acids During the Glucose Tolerance Test Represent Tissue-Specific Insulin Sensitivity. Front Endocrinol (Lausanne). 2019 Dec 17;10:870. doi: 10.3389/fendo.2019.00870. eCollection 2019. [PubMed:31920980 ]
  21. Forni S, Fu X, Palmer SE, Sweetman L: Rapid determination of C4-acylcarnitine and C5-acylcarnitine isomers in plasma and dried blood spots by UPLC-MS/MS as a second tier test following flow-injection MS/MS acylcarnitine profile analysis. Mol Genet Metab. 2010 Sep;101(1):25-32. doi: 10.1016/j.ymgme.2010.05.012. Epub 2010 Jun 10. [PubMed:20591710 ]
  22. Roy C, Tremblay PY, Anassour-Laouan-Sidi E, Lucas M, Forest JC, Giguere Y, Ayotte P: Risk of gestational diabetes mellitus in relation to plasma concentrations of amino acids and acylcarnitines: A nested case-control study. Diabetes Res Clin Pract. 2018 Jun;140:183-190. doi: 10.1016/j.diabres.2018.03.058. Epub 2018 Apr 4. [PubMed:29626588 ]
  23. Jeter CB, Hergenroeder GW, Ward NH 3rd, Moore AN, Dash PK: Human mild traumatic brain injury decreases circulating branched-chain amino acids and their metabolite levels. J Neurotrauma. 2013 Apr 15;30(8):671-9. doi: 10.1089/neu.2012.2491. Epub 2013 Apr 6. [PubMed:23560894 ]
  24. Wang Y, Sun W, Zheng J, Xu C, Wang X, Li T, Tang Y, Li Z: Urinary metabonomic study of patients with acute coronary syndrome using UPLC-QTOF/MS. J Chromatogr B Analyt Technol Biomed Life Sci. 2018 Nov 15;1100-1101:122-130. doi: 10.1016/j.jchromb.2018.10.005. Epub 2018 Oct 7. [PubMed:30316136 ]
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