Carnosine

Not to be confused with carnitine.

Carnosine (beta-alanyl-L-histidine) is a dipeptide molecule, made up of the amino acids beta-alanine and histidine. It is highly concentrated in muscle and brain tissues.^{[citation needed]} Carnosine was discovered by Russian chemist Vladimir Gulevich.^[1]

Carnosine

Names
IUPAC name β-Alanylhistidine
Systematic IUPAC name (2S)-2-(3-Aminopropanamido)-3-(3H-imidazol-4-yl)propanoic acid
Other names β-Alanyl-L-histidine
Identifiers
CAS Number	305-84-0 Y
3D model (JSmol)	Interactive image Interactive image
ChEBI	CHEBI:15727 Y
ChEMBL	ChEMBL242948 Y
ChemSpider	388363 Y
ECHA InfoCard	100.005.610
IUPHAR/BPS	4559
KEGG	C00386 Y
PubChem CID	439224
UNII	8HO6PVN24W Y
CompTox Dashboard (EPA)	DTXSID80879594
InChI InChI=1S/C9H14N4O3/c10-2-1-8(14)13-7(9(15)16)3-6-4-11-5-12-6/h4-5,7H,1-3,10H2,(H,11,12)(H,13,14)(H,15,16)/t7-/m0/s1 Y Key: CQOVPNPJLQNMDC-ZETCQYMHSA-N Y InChI=1/C9H14N4O3/c10-2-1-8(14)13-7(9(15)16)3-6-4-11-5-12-6/h4-5,7H,1-3,10H2,(H,11,12)(H,13,14)(H,15,16)/t7-/m0/s1 Key: CQOVPNPJLQNMDC-ZETCQYMHBX
SMILES O=C(O)C(NC(=O)CCN)Cc1c[nH]cn1 c1c(nc[nH]1)C[C@@H](C(=O)O)NC(=O)CCN
Properties
Chemical formula	C9H14N4O3
Molar mass	226.236 g·mol−1
Appearance	Crystalline solid
Melting point	253 °C (487 °F; 526 K) (decomposition)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Carnosine is naturally produced by the body in the liver^[2] from beta-alanine and histidine. Like carnitine, carnosine is composed of the root word carn, meaning "flesh", alluding to its prevalence in meat.^[3] There are no plant-based sources of carnosine.^[4] Carnosine is readily available as a synthetic nutritional supplement.

Carnosine can chelate divalent metal ions.^[5] Carnosine is also considered a geroprotectant.^[6]

Products containing carnosine are also used in topical preparations to reduce wrinkles on the skin.^[7]

Carnosine may increase the Hayflick limit in human fibroblasts, it also appears to reduce the rate of telomere shortening.^[8] This could potentially promote the growth of certain cancers that thrive due to telomere preservation.^[7]

Biosynthesis

Carnosine is synthesized within the body from beta-alanine and histidine. Beta-alanine is a product of pyrimidine catabolism^[9] and histidine is an essential amino acid. Since beta-alanine is the limiting substrate, supplementing just beta-alanine effectively increases the intramuscular concentration of carnosine.^[10][11]

Physiological effects

pH buffer

Carnosine has a pK_a value of 6.83, making it a good buffer for the pH range of animal muscles.^[12] Since beta-alanine is not incorporated into proteins, carnosine can be stored at relatively high concentrations (millimolar). Occurring at 17–25 mmol/kg (dry muscle),^[13] carnosine (β-alanyl-L-histidine) is an important intramuscular buffer, constituting 10-20% of the total buffering capacity in type I and II muscle fibres.

Anti-oxidant

Carnosine has been shown to scavenge reactive oxygen species (ROS) as well as alpha-beta unsaturated aldehydes formed from peroxidation of cell membrane fatty acids during oxidative stress. It also buffers pH in muscle cells, and acts as a neurotransmitter in the brain. It is also a zwitterion, a neutral molecule with a positive and negative end.^{[citation needed]}

Antiglycating

Carnosine acts as an antiglycating agent, reducing the rate of formation of advanced glycation end-products (substances that can be a factor in the development or worsening of many degenerative diseases, such as diabetes, atherosclerosis, chronic kidney failure, and Alzheimer's disease^[14]), and ultimately reducing development of atherosclerotic plaque build-up.^[15][16][17]

Geroprotective

Carnosine is considered as a geroprotector.^[18] Carnosine can increase the Hayflick limit in human fibroblasts,^[19] as well as appearing to reduce the telomere shortening rate.^[20] Carnosine may also slow aging through its anti-glycating properties (chronic glycolyating is speculated to accelerate aging).^[21]

Other

Carnosine can chelate divalent metal ions.^[15][22] It has been suggested that binding Ca²⁺ may displace protons, thereby providing a link between Ca²⁺ and H⁺ buffering. ^[23] However, there is still controversy as to how much Ca²⁺ is bound to carnosine under physiological conditions. ^[24]

See also

• Acetylcarnosine, a similar molecule used to treat lens cataracts
• Anserine, another dipeptide antioxidant (found in birds)
• Carnosine synthase, an enzyme that helps carnosine production
• Carnosinemia, a disease of excess carnosine due to an enzyme defect/deficiency