Carnosine

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.Template:Citation needed Carnosine was discovered by Russian chemist Vladimir Gulevich.<ref>Template:Cite journal</ref>

Carnosine is naturally produced by the body in the liver<ref>Template:Cite journal</ref> from beta-alanine and histidine. Like carnitine, carnosine is composed of the root word carn, meaning "flesh", alluding to its prevalence in meat.<ref>Template:Cite journal</ref> There are no plant-based sources of carnosine.<ref>Template:Cite book</ref> Carnosine is readily available as a synthetic nutritional supplement.

Carnosine can chelate divalent metal ions.<ref name="pmid158723113">Template:Cite journal</ref> Carnosine is also considered a geroprotectant.<ref>Template:Cite journal</ref>

Products containing carnosine are also used in topical preparations to reduce wrinkles on the skin.<ref name="Schwarz2010">Template:Cite journal</ref>

Carnosine may increase the Hayflick limit in human fibroblasts, it also appears to reduce the rate of telomere shortening.<ref>Template:Cite journal</ref> This could potentially promote the growth of certain cancers that thrive due to telomere preservation.<ref name="Schwarz2010" />

Biosynthesis

Carnosine is synthesized within the body from beta-alanine and histidine. Beta-alanine is a product of pyrimidine catabolism<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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.<ref>Template:Cite journal</ref><ref name="Hill2007">Template:Cite journal</ref>

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.<ref>Template:Cite journal</ref> 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),<ref>Template:Cite journal</ref> 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.Template: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<ref>Template:Cite journal</ref>), and ultimately reducing development of atherosclerotic plaque build-up.<ref name="pmid15872311">Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

Geroprotective

Carnosine is considered as a geroprotector.<ref>Template:Cite journal</ref> Carnosine can increase the Hayflick limit in human fibroblasts,<ref>Template:Cite journal</ref> as well as appearing to reduce the telomere shortening rate.<ref>Template:Cite journal</ref> Carnosine may also slow aging through its anti-glycating properties (chronic glycolyating is speculated to accelerate aging).<ref>Template:Cite journal</ref>

Other

Carnosine can chelate divalent metal ions.<ref name="pmid15872311" /><ref>Template:Cite journal</ref> It has been suggested that binding Ca²⁺ may displace protons, thereby providing a link between Ca²⁺ and H⁺ buffering. <ref>Template:Cite journal</ref> However, there is still controversy as to how much Ca²⁺ is bound to carnosine under physiological conditions. <ref>Template:Cite journal</ref>

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