Acetylcarnitine

Last updated
Acetylcarnitine
Acetylcarnitine.svg
Clinical data
AHFS/Drugs.com International Drug Names
Routes of
administration
Oral
ATC code
Legal status
Legal status
Pharmacokinetic data
Bioavailability >10%
Elimination half-life 28.9 - 35.9 hours [1]
Identifiers
  • (R)-3-Acetyloxy-4-trimethylammonio-butanoate
CAS Number
PubChem CID
DrugBank
ChemSpider
UNII
ChEBI
ChEMBL
CompTox Dashboard (EPA)
ECHA InfoCard 100.130.594 OOjs UI icon edit-ltr-progressive.svg
Chemical and physical data
Formula C9H17NO4
Molar mass 203.238 g·mol−1
3D model (JSmol)
  • [O-]C(=O)C[C@@H](OC(=O)C)C[N+](C)(C)C
  • InChI=1S/C9H17NO4/c1-7(11)14-8(5-9(12)13)6-10(2,3)4/h8H,5-6H2,1-4H3/t8-/m1/s1 Yes check.svgY
  • Key:RDHQFKQIGNGIED-MRVPVSSYSA-N Yes check.svgY
 X mark.svgNYes check.svgY  (what is this?)    (verify)

Acetyl-L-carnitine, ALCAR or ALC, is an acetylated form of L-carnitine. It is naturally produced by the human body, and it is available as a dietary supplement. Acetylcarnitine is broken down in the blood by plasma esterases to carnitine which is used by the body to transport fatty acids into the mitochondria for breakdown and energy production.

Contents

Biochemical production and action

Carnitine is both a nutrient and made by the body as needed; it serves as a substrate for important reactions in which it accepts and gives up an acyl group. Acetylcarnitine is the most abundant naturally occurring derivative and is formed in the reaction:

acetyl-CoA + carnitine CoA + acetylcarnitine

where the acetyl group displaces the hydrogen atom in the central hydroxyl group of carnitine. [2] [3] Coenzyme A (CoA) plays a key role in the Krebs cycle in mitochondria, which is essential for the production of ATP, which powers many reactions in cells; acetyl-CoA is the primary substrate for the Krebs cycle, once it is de-acetylated, it must be re-charged with an acetyl-group in order for the Krebs cycle to keep working. [3]

Most cell types appear to have transporters to import carnitine and export acyl-carnitines, which seems to be a mechanism to dispose of longer-chain moieties; however many cell types can also import ALCAR. [2]

Within cells, carnitine plays a key role in importing acyl-CoA into mitochondria; the acyl-group of the acyl-CoA is transferred to carnitine, and the acyl-carnitine is imported through both mitochondrial membranes before being transferred to a CoA molecule, which is then beta oxidized to acetyl-CoA. A separate set of enzymes and transporters also plays a buffering role by eliminating acetyl-CoA from inside mitochondria created by the pyruvate dehydrogenase complex that is in excess of its utilization by the Krebs cycle; carnitine accepts the acetyl moiety and becomes ALCAR, which is then transported out of the mitochondria and into the cytosol, leaving free CoA inside the mitochondria ready to accept new import of fatty acid chains. [3] ALCAR in the cytosol can also form a pool of acetyl-groups for CoA, should the cell need it. [3]

Excess acetyl-CoA causes more carbohydrates to be used for energy at the expense of fatty acids. This occurs by different mechanisms inside and outside the mitochondria. ALCAR transport decreases acetyl-CoA inside the mitochondria, but increases it outside. [4] [5]

Health effects

Carnitine and ALCAR supplements carry warnings of a risk that they promote seizures in people with epilepsy, but a 2016 review found this risk to be based only on animal trials. [6]

Research

Reviews

Studies

Related Research Articles

<span class="mw-page-title-main">Ketosis</span> Using body fats as fuel instead of carbohydrates

Ketosis is a metabolic state characterized by elevated levels of ketone bodies in the blood or urine. Physiological ketosis is a normal response to low glucose availability. In physiological ketosis, ketones in the blood are elevated above baseline levels, but the body's acid–base homeostasis is maintained. This contrasts with ketoacidosis, an uncontrolled production of ketones that occurs in pathologic states and causes a metabolic acidosis, which is a medical emergency. Ketoacidosis is most commonly the result of complete insulin deficiency in type 1 diabetes or late-stage type 2 diabetes. Ketone levels can be measured in blood, urine or breath and are generally between 0.5 and 3.0 millimolar (mM) in physiological ketosis, while ketoacidosis may cause blood concentrations greater than 10 mM.

<span class="mw-page-title-main">Dietary supplement</span> Product providing additional nutrients

A dietary supplement is a manufactured product intended to supplement a person's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources, or that are synthetic. The classes of nutrient compounds in supplements include vitamins, minerals, fiber, fatty acids, and amino acids. Dietary supplements can also contain substances that have not been confirmed as being essential to life, and so are not nutrients per se, but are marketed as having a beneficial biological effect, such as plant pigments or polyphenols. Animals can also be a source of supplement ingredients, such as collagen from chickens or fish for example. These are also sold individually and in combination, and may be combined with nutrient ingredients. The European Commission has also established harmonized rules to help insure that food supplements are safe and appropriately labeled.

<span class="mw-page-title-main">Acetyl-CoA</span> Chemical compound

Acetyl-CoA is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function is to deliver the acetyl group to the citric acid cycle to be oxidized for energy production.

<span class="mw-page-title-main">Carnitine</span> Amino acid active in mitochondria

Carnitine is a quaternary ammonium compound involved in metabolism in most mammals, plants, and some bacteria. 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. Given its key metabolic roles, carnitine is concentrated in tissues like skeletal and cardiac muscle that metabolize fatty acids as an energy source. Generally individuals, including strict vegetarians, synthesize enough L-carnitine in vivo.

<span class="mw-page-title-main">Ketogenesis</span> Chemical synthesis of ketone bodies

Ketogenesis is the biochemical process through which organisms produce ketone bodies by breaking down fatty acids and ketogenic amino acids. The process supplies energy to certain organs, particularly the brain, heart and skeletal muscle, under specific scenarios including fasting, caloric restriction, sleep, or others.

<span class="mw-page-title-main">Duloxetine</span> Antidepressant medication used also for treatment of anxiety and chronic pain

Duloxetine, sold under the brand name Cymbalta among others, is a medication used to treat major depressive disorder, generalized anxiety disorder, obsessive-compulsive disorder, fibromyalgia, neuropathic pain and central sensitization. It is taken by mouth.

<span class="mw-page-title-main">Peripheral neuropathy</span> Nervous system disease affecting nerves beyond the brain and spinal cord

Peripheral neuropathy, often shortened to neuropathy, refers to damage or disease affecting the nerves. Damage to nerves may impair sensation, movement, gland function, and/or organ function depending on which nerve fibers are affected. Neuropathies affecting motor, sensory, or autonomic nerve fibers result in different symptoms. More than one type of fiber may be affected simultaneously. Peripheral neuropathy may be acute or chronic, and may be reversible or permanent.

Neuropathic pain is pain caused by a lesion or disease of the somatosensory nervous system. Neuropathic pain may be associated with abnormal sensations called dysesthesia or pain from normally non-painful stimuli (allodynia). It may have continuous and/or episodic (paroxysmal) components. The latter resemble stabbings or electric shocks. Common qualities include burning or coldness, "pins and needles" sensations, numbness and itching.

Fatty acid metabolism consists of various metabolic processes involving or closely related to fatty acids, a family of molecules classified within the lipid macronutrient category. These processes can mainly be divided into (1) catabolic processes that generate energy and (2) anabolic processes where they serve as building blocks for other compounds.

In biochemistry and metabolism, beta oxidation (also β-oxidation) is the catabolic process by which fatty acid molecules are broken down in the cytosol in prokaryotes and in the mitochondria in eukaryotes to generate acetyl-CoA. Acetyl-CoA enters the citric acid cycle, generating NADH and FADH2, which are electron carriers used in the electron transport chain. It is named as such because the beta carbon of the fatty acid chain undergoes oxidation and is converted to a carbonyl group to start the cycle all over again. Beta-oxidation is primarily facilitated by the mitochondrial trifunctional protein, an enzyme complex associated with the inner mitochondrial membrane, although very long chain fatty acids are oxidized in peroxisomes.

<span class="mw-page-title-main">Acetyl-CoA carboxylase</span> Enzyme that regulates the metabolism of fatty acids

Acetyl-CoA carboxylase (ACC) is a biotin-dependent enzyme that catalyzes the irreversible carboxylation of acetyl-CoA to produce malonyl-CoA through its two catalytic activities, biotin carboxylase (BC) and carboxyltransferase (CT). ACC is a multi-subunit enzyme in most prokaryotes and in the chloroplasts of most plants and algae, whereas it is a large, multi-domain enzyme in the cytoplasm of most eukaryotes. The most important function of ACC is to provide the malonyl-CoA substrate for the biosynthesis of fatty acids. The activity of ACC can be controlled at the transcriptional level as well as by small molecule modulators and covalent modification. The human genome contains the genes for two different ACCs—ACACA and ACACB.

<span class="mw-page-title-main">Malonyl-CoA</span> Chemical compound

Malonyl-CoA is a coenzyme A derivative of malonic acid.

<span class="mw-page-title-main">Carnitine palmitoyltransferase II deficiency</span> Medical condition

Carnitine palmitoyltransferase II deficiency, sometimes shortened to CPT-II or CPT2, is an autosomal recessively inherited genetic metabolic disorder characterized by an enzymatic defect that prevents long-chain fatty acids from being transported into the mitochondria for utilization as an energy source. The disorder presents in one of three clinical forms: lethal neonatal, severe infantile hepatocardiomuscular and myopathic.

β-Hydroxybutyric acid Chemical compound

β-Hydroxybutyric acid, also known as 3-hydroxybutyric acid or BHB, is an organic compound and a beta hydroxy acid with the chemical formula CH3CH(OH)CH2CO2H; its conjugate base is β-hydroxybutyrate, also known as 3-hydroxybutyrate. β-Hydroxybutyric acid is a chiral compound with two enantiomers: D-β-hydroxybutyric acid and L-β-hydroxybutyric acid. Its oxidized and polymeric derivatives occur widely in nature. In humans, D-β-hydroxybutyric acid is one of two primary endogenous agonists of hydroxycarboxylic acid receptor 2 (HCA2), a Gi/o-coupled G protein-coupled receptor (GPCR).

<span class="mw-page-title-main">Acyl-CoA</span> Group of coenzymes that metabolize fatty acids

Acyl-CoA is a group of CoA-based coenzymes that metabolize carboxylic acids. Fatty acyl-CoA's are susceptible to beta oxidation, forming, ultimately, acetyl-CoA. The acetyl-CoA enters the citric acid cycle, eventually forming several equivalents of ATP. In this way, fats are converted to ATP, the common biochemical energy carrier.

<span class="mw-page-title-main">Carnitine palmitoyltransferase I</span> Enzyme found in humans

Carnitine palmitoyltransferase I (CPT1) also known as carnitine acyltransferase I, CPTI, CAT1, CoA:carnitine acyl transferase (CCAT), or palmitoylCoA transferase I, is a mitochondrial enzyme responsible for the formation of acyl carnitines by catalyzing the transfer of the acyl group of a long-chain fatty acyl-CoA from coenzyme A to l-carnitine. The product is often palmitoylcarnitine, but other fatty acids may also be substrates. It is part of a family of enzymes called carnitine acyltransferases. This "preparation" allows for subsequent movement of the acyl carnitine from the cytosol into the intermembrane space of mitochondria.

<span class="mw-page-title-main">Carnitine O-acetyltransferase</span> Enzyme

Carnitine O-acetyltransferase also called carnitine acetyltransferase is an enzyme that encoded by the CRAT gene that catalyzes the chemical reaction

<span class="mw-page-title-main">Carnitine O-octanoyltransferase</span>

Carnitine O-octanoyltransferase is a member of the transferase family, more specifically a carnitine acyltransferase, a type of enzyme which catalyzes the transfer of acyl groups from acyl-CoAs to carnitine, generating CoA and an acyl-carnitine. Specifically, CROT catalyzes the chemical reaction:

Etomoxir, or rac-Ethyl 2-[6-(4-chlorophenoxy)hexyl]oxirane-2-carboxylate, in form of the dextrorotatory (R)-(+)- enantiomer, is an irreversible inhibitor of carnitine palmitoyltransferase-1 on the inner face of the outer mitochondrial membrane. The actual inhibitor – (R)-(+)-etomoxir-Coenzym A ester – is formed in an intracellular process. The middle inhibitor concentration for the inhibition of the CPT-1 in the liver, heart, and muscle mitochondria of rats lies in between 5 and 20 nmol/l, depending on the animal's state of metabolism. (+)-Etomoxir is a colourness solid with a melting point of 38 °C (311 K). The sodium salt of (+)-Etomoxir is water-soluble. The (S)-(-)-enantiomer of Etomoxir does not block CPT-1.

β-Hydroxy β-methylbutyryl-CoA Chemical compound

β-Hydroxy β-methylbutyryl-coenzyme A (HMB-CoA), also known as 3-hydroxyisovaleryl-CoA, is a metabolite of L-leucine that is produced in the human body. Its immediate precursors are β-hydroxy β-methylbutyric acid (HMB) and β-methylcrotonoyl-CoA (MC-CoA). It can be metabolized into HMB, MC-CoA, and HMG-CoA in humans.

References

  1. Cao Y, Wang YX, Liu CJ, Wang LX, Han ZW, Wang CB (February 2009). "Comparison of pharmacokinetics of L-carnitine, acetyl-L-carnitine and propionyl-L-carnitine after single oral administration of L-carnitine in healthy volunteers". Clinical and Investigative Medicine. 32 (1): E13–E19. doi: 10.25011/cim.v32i1.5082 . PMID   19178874.
  2. 1 2 Bieber LL (1988). "Carnitine". Annual Review of Biochemistry. 57: 261–283. doi:10.1146/annurev.bi.57.070188.001401. PMID   3052273.
  3. 1 2 3 4 5 Stephens FB, Constantin-Teodosiu D, Greenhaff PL (June 2007). "New insights concerning the role of carnitine in the regulation of fuel metabolism in skeletal muscle". The Journal of Physiology. 581 (Pt 2): 431–444. doi:10.1113/jphysiol.2006.125799. PMC   2075186 . PMID   17331998.
  4. Kiens B (January 2006). "Skeletal muscle lipid metabolism in exercise and insulin resistance". Physiological Reviews. 86 (1): 205–243. doi:10.1152/physrev.00023.2004. PMID   16371598.
  5. Lopaschuk GD, Gamble J (October 1994). "The 1993 Merck Frosst Award. Acetyl-CoA carboxylase: an important regulator of fatty acid oxidation in the heart". Canadian Journal of Physiology and Pharmacology. 72 (10): 1101–1109. doi:10.1139/y94-156. PMID   7882173.
  6. Zeiler FA, Sader N, Gillman LM, West M (March 2016). "Levocarnitine induced seizures in patients on valproic acid: A negative systematic review". Seizure. 36: 36–39. doi: 10.1016/j.seizure.2016.01.020 . PMID   26889779.
  7. Li S, Li Q, Li Y, Li L, Tian H, Sun X (2015-01-01). "Acetyl-L-carnitine in the treatment of peripheral neuropathic pain: a systematic review and meta-analysis of randomized controlled trials". PLOS ONE. 10 (3): e0119479. Bibcode:2015PLoSO..1019479L. doi: 10.1371/journal.pone.0119479 . PMC   4353712 . PMID   25751285.
  8. Veronese N (2017). "Effect of acetyl-l-carnitine in the treatment of diabetic peripheral neuropathy: A systematic review and meta-analysis". European Geriatric Medicine. 8 (2): 117–122. doi:10.1016/j.eurger.2017.01.002. hdl: 10138/235591 . S2CID   56342481.
  9. Rolim LC, da Silva EM, Flumignan RL, Abreu MM, Dib SA (June 2019). "Acetyl-L-carnitine for the treatment of diabetic peripheral neuropathy". The Cochrane Database of Systematic Reviews. 2019 (6): CD011265. doi:10.1002/14651858.CD011265.pub2. PMC   6953387 . PMID   31201734.
  10. Schloss JM, Colosimo M, Airey C, Masci PP, Linnane AW, Vitetta L (December 2013). "Nutraceuticals and chemotherapy induced peripheral neuropathy (CIPN): a systematic review". Clinical Nutrition. 32 (6): 888–893. doi:10.1016/j.clnu.2013.04.007. PMID   23647723.
  11. Brami C, Bao T, Deng G (February 2016). "Natural products and complementary therapies for chemotherapy-induced peripheral neuropathy: A systematic review". Critical Reviews in Oncology/Hematology. 98: 325–334. doi:10.1016/j.critrevonc.2015.11.014. PMC   4727999 . PMID   26652982.
  12. Ahmadi S, Bashiri R, Ghadiri-Anari A, Nadjarzadeh A (December 2016). "Antioxidant supplements and semen parameters: An evidence based review". International Journal of Reproductive Biomedicine. 14 (12): 729–736. doi:10.29252/ijrm.14.12.729 (inactive 1 November 2024). PMC   5203687 . PMID   28066832.{{cite journal}}: CS1 maint: DOI inactive as of November 2024 (link)
  13. Arcaniolo D, Favilla V, Tiscione D, Pisano F, Bozzini G, Creta M, et al. (September 2014). "Is there a place for nutritional supplements in the treatment of idiopathic male infertility?". Archivio Italiano di Urologia, Andrologia. 86 (3): 164–170. doi: 10.4081/aiua.2014.3.164 . PMID   25308577.
  14. Hudson S, Tabet N (2003). "Acetyl-L-carnitine for dementia". The Cochrane Database of Systematic Reviews (Systematic review). 2003 (2): CD003158. doi:10.1002/14651858.CD003158. PMC   6991156 . PMID   12804452.
  15. Wang SM, Han C, Lee SJ, Patkar AA, Masand PS, Pae CU (June 2014). "A review of current evidence for acetyl-l-carnitine in the treatment of depression". Journal of Psychiatric Research. 53: 30–37. doi:10.1016/j.jpsychires.2014.02.005. PMID   24607292.
  16. Kriston L, von Wolff A, Westphal A, Hölzel LP, Härter M (August 2014). "Efficacy and acceptability of acute treatments for persistent depressive disorder: a network meta-analysis". Depression and Anxiety. 31 (8): 621–630. doi: 10.1002/da.22236 . PMID   24448972. S2CID   41163109.
  17. Veronese N, Stubbs B, Solmi M, Ajnakina O, Carvalho AF, Maggi S (Feb–Mar 2018). "Acetyl-L-Carnitine Supplementation and the Treatment of Depressive Symptoms: A Systematic Review and Meta-Analysis". Psychosomatic Medicine. 80 (2): 154–159. doi:10.1097/PSY.0000000000000537. PMID   29076953. S2CID   7649619.
  18. Rueda JR, Guillén V, Ballesteros J, Tejada MI, Solà I (May 2015). "L-acetylcarnitine for treating fragile X syndrome". The Cochrane Database of Systematic Reviews. 19 (5): CD010012. doi:10.1002/14651858.CD010012.pub2. PMC   10849109 . PMID   25985235.
  19. Jawaro T, Yang A, Dixit D, Bridgeman MB (July 2016). "Management of Hepatic Encephalopathy: A Primer". The Annals of Pharmacotherapy. 50 (7): 569–577. doi:10.1177/1060028016645826. PMC   1503997 . PMID   27126547. S2CID   32765158.
  20. 1 2 Liu J, Head E, Gharib AM, Yuan W, Ingersoll RT, Hagen TM, et al. (February 2002). "Memory loss in old rats is associated with brain mitochondrial decay and RNA/DNA oxidation: Partial reversal by feeding acetyl-L-carnitine and/or R -α-lipoic acid". Proceedings of the National Academy of Sciences of the United States of America. 99 (4): 2356–2361. doi: 10.1073/pnas.261709299 . PMC   122369 . PMID   11854529.

Further reading