Carnitine

Carnitine
Clinical data


AHFS/Drugs.com	Micromedex Detailed Consumer Information
Pregnancy category	US: B (No risk in non-human studies)
Routes of administration	Oral, intravenous
ATC code	A16AA01 (WHO) (L form)
Legal status
Legal status	US: OTC
Pharmacokinetic data
Bioavailability	<10%
Protein binding	None
Metabolism	slightly
Excretion	Urine (>95%)
Identifiers
IUPAC name 3-Hydroxy-4-(trimethylazaniumyl)butanoate
CAS Number	541-15-1^Y
PubChem (CID)	288
DrugBank	DB00583^N
ChemSpider	282^Y
UNII	0G389FZZ9M^Y
KEGG	C00318^Y
ChEBI	CHEBI:17126^Y
ChEMBL	CHEMBL172513^Y
Chemical and physical data
Formula	C₇H₁₅NO₃
Molar mass	161.199 g/mol
3D model (Jmol)	Interactive image
SMILES C[N+](C)(C)CC(CC(=O)[O-])O
InChI InChI=1S/C7H15NO3/c1-8(2,3)5-6(9)4-7(10)11/h6,9H,4-5H2,1-3H3^Y Key:PHIQHXFUZVPYII-UHFFFAOYSA-N^Y
^NY (what is this?)

Carnitine(β-hydroxy-γ-N-trimethylaminobutyric acid,3-hydroxy-4-N,N,N- trimethylaminobutyrate) is a quaternary ammonium compound involved in metabolism in most mammals, plants and some bacteria. Carnitine may exist in two isomers, labeled D-Carnitine and L-Carnitine, as they are optically active. At room temperature, pure carnitine is a white powder, and a water soluble zwitterion with low toxicity. Carnitine only exists in animals as the L enantiomer, and DL-Carnitine is toxic as it is inactive but inhibits the activity of L-Carnitine. Carnitine, discovered in 1905 with a high density in muscle tissue was labeled Vitamin B_T, however as carnitine is synthesized in the human body, it is not a vitamin. Carnitine is involved in the oxidation of fatty acids, and involved in systemic primary carnitine deficiency. It has been researched for preventing and treating other conditions, and may be used as an athletic performance enhancer.

Many eukaryotes have the ability to synthesize carnitine, including humans. Humans synthesize carnitine from the substrate TML(6-N-Trimethyllysine), derived from the methylation of lysine. TML is then hydroxylated into HTML by TML dioxygenase, requiring the presence of ascorbic acid. HTML is then cleaved by HTML aldose, yielding 4-trimethylaminobutyraldehyde(TMABA) and glycine. TMABA is then dehydrogenated into gamma-butyrobetaine, in an NAD+ dependent reaction catalyzed by TMABA dehydrogenase. Gamma butyrobetaine is then hydroxylated by gamma butyrobetaine hydroxylase into L-Carnitine, requiring Fe2+.

Carnitine is involved in transporting fatty acids across the mitochondrial membrane, by forming a long chain acetylcarnitine ester and being transported by Carnitine palmitoyltransferase I and Carnitine palmitoyltransferase II. Carnitine also plays a role in stabilizing Acetyl-CoA and coenzyme A levels through the ability to receive or give an acetyl group.

Carnitine deficiency caused by a genetic defect in carnitine transport occurs in roughly 1 in 50,000 in the US. SPDC is characterized by various cardiological, metabolic and musculoskeletal symptoms that vary widely in age of onset and presentation. Prognosis is generally good with carnitine supplementation.

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Wikipedia