Carnitine

Carnitine
Clinical data
AHFS/Drugs.comMicromedex Detailed Consumer Information
Routes of
administration		Oral, intravenous
ATC code
  • A16AA01 (WHO) (l-form)
Legal status
Legal status
Pharmacokinetic data
Bioavailability<10%
Protein bindingNone
Metabolismslightly [clarification needed]
ExcretionUrine (>95%)
Identifiers
  • 3-hydroxy-4-(trimethylazaniumyl)butanoate
CAS Number
PubChem CID
DrugBank
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
CompTox Dashboard (EPA)
ECHA InfoCard100.006.343 Edit this at Wikidata
Chemical and physical data
FormulaC7H15NO3
Molar mass161.201 g·mol−1
3D model (JSmol)
  • C[N+](C)(C)CC(CC(=O)[O-])O
  • InChI=1S/C7H15NO3/c1-8(2,3)5-6(9)4-7(10)11/h6,9H,4-5H2,1-3H3 checkY
  • Key:PHIQHXFUZVPYII-UHFFFAOYSA-N checkY
 ☒NcheckY (what is this?)  (verify)

Carnitine is a quaternary ammonium compound involved in metabolism in most mammals, plants, and some bacteria.[1][2][3][4] In support of energy metabolism, carnitine transports long-chain fatty acids from the cytosol into mitochondria to be oxidized for free energy production, and also participates in removing products of metabolism from cells.[3] Given its key metabolic roles, carnitine is concentrated in tissues like skeletal and cardiac muscle that metabolize fatty acids as an energy source.[3] Generally individuals, including strict vegetarians, synthesize enough L-carnitine in vivo.[1]

Carnitine exists as one of two stereoisomers: the two enantiomers d-carnitine (S-(+)-) and l-carnitine (R-(−)-).[5] Both are biologically active, but only l-carnitine naturally occurs in animals, and d-carnitine is toxic as it inhibits the activity of the l-form.[6] At room temperature, pure carnitine is a whiteish powder, and a water-soluble zwitterion with relatively low toxicity. Derived from amino acids,[7] carnitine was first extracted from meat extracts in 1905, leading to its name from Latin, "caro/carnis" or flesh.[2]

Some individuals with genetic or medical disorders (such as preterm infants) cannot make enough carnitine, requiring dietary supplementation.[1][3][4] Despite common carnitine supplement consumption among athletes for improved exercise performance or recovery, there is insufficient high-quality clinical evidence to indicate it provides any benefit.[3][4]

  1. ^ a b c "L-Carnitine". Micronutrient Information Center, Linus Pauling Institute, Oregon State University, Corvallis, OR. 2019-12-01. Retrieved 2020-04-29.
  2. ^ a b Bremer J (October 1983). "Carnitine--metabolism and functions". Physiological Reviews. 63 (4): 1420–80. doi:10.1152/physrev.1983.63.4.1420. PMID 6361812.
  3. ^ a b c d e "Carnitine". Office of Dietary Supplements, US National Institutes of Health. 2017-10-10. Retrieved 2020-04-29.
  4. ^ a b c "L-carnitine: Uses, benefits and dosage". Drugs.com. 2020-01-20. Retrieved 2020-04-29.
  5. ^ "Levocarnitine". PubChem, National Library of Medicine, US National Institutes of Health. 2020-04-25. Retrieved 2020-04-29.
  6. ^ Matsuoka M, Igisu H (July 1993). "Comparison of the effects of L-carnitine, D-carnitine and acetyl-L-carnitine on the neurotoxicity of ammonia". Biochemical Pharmacology. 46 (1): 159–64. doi:10.1016/0006-2952(93)90360-9. PMID 8347126.
  7. ^ Cox RA, Hoppel CL (December 1973). "Biosynthesis of carnitine and 4-N-trimethylaminobutyrate from 6-N-trimethyl-lysine". The Biochemical Journal. 136 (4): 1083–90. doi:10.1042/bj1361083. PMC 1166060. PMID 4786530.