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][irrelevant citation]
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][irrelevant citation]
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 pKa 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 17–25mmol/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]
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 chelatedivalent 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)
↑Alan R. Hipkiss (2009). "Chapter 3: Carnosine and Its Possible Roles in Nutrition and Health". Advances in Food and Nutrition Research.
↑Reddy, V. P.; Garrett, MR; Perry, G; Smith, MA (2005). "Carnosine: A Versatile Antioxidant and Antiglycating Agent". Science of Aging Knowledge Environment. 2005 (18): pe12. doi:10.1126/sageke.2005.18.pe12. PMID15872311.
↑Boldyrev, A. A.; Stvolinsky, S. L.; Fedorova, T. N.; Suslina, Z. A. (2010). "Carnosine as a natural antioxidant and geroprotector: From molecular mechanisms to clinical trials". Rejuvenation Research. 13 (2–3): 156–8. doi:10.1089/rej.2009.0923. PMID20017611.
↑Shao, Lan; Li, Qing-Huan; Tan, Zheng (2004). "L-Carnosine reduces telomere damage and shortening rate in cultured normal fibroblasts". Biochemical and Biophysical Research Communications. 324 (2): 931–6. doi:10.1016/j.bbrc.2004.09.136. PMID15474517.
↑"beta-ureidopropionate + H2O => beta-alanine + NH4+ + CO2". reactome. Archived from the original on 2013-10-23. Retrieved 2020-02-08. Cytosolic 3-ureidopropionase catalyzes the reaction of 3-ureidopropionate and water to form beta-alanine, CO2, and NH3 (van Kuilenberg et al. 2004).
↑Derave W, Ozdemir MS, Harris R, Pottier A, Reyngoudt H, Koppo K, Wise JA, Achten E (August 9, 2007). "Beta-alanine supplementation augments muscle carnosine content and attenuates fatigue during repeated isokinetic contraction bouts in trained sprinters". J Appl Physiol. 103 (5): 1736–43. doi:10.1152/japplphysiol.00397.2007. PMID17690198. S2CID6990201.
↑Hill CA, Harris RC, Kim HJ, Harris BD, Sale C, Boobis LH, Kim CK, Wise JA (2007). "Influence of beta-alanine supplementation on skeletal muscle carnosine concentrations and high intensity cycling capacity". Amino Acids. 32 (2): 225–33. doi:10.1007/s00726-006-0364-4. PMID16868650. S2CID23988054.
↑Boldyrev, A. A.; Stvolinsky, S. L.; Fedorova, T. N.; Suslina, Z. A. (2010). "Carnosine as a natural antioxidant and geroprotector: From molecular mechanisms to clinical trials". Rejuvenation Research. 13 (2–3): 156–8. doi:10.1089/rej.2009.0923. PMID20017611.
↑McFarland, G; Holliday, R (1994). "Retardation of the Senescence of Cultured Human Diploid Fibroblasts by Carnosine". Experimental Cell Research. 212 (2): 167–75. doi:10.1006/excr.1994.1132. PMID8187813.
↑Shao, Lan; Li, Qing-Huan; Tan, Zheng (2004). "L-Carnosine reduces telomere damage and shortening rate in cultured normal fibroblasts". Biochemical and Biophysical Research Communications. 324 (2): 931–6. doi:10.1016/j.bbrc.2004.09.136. PMID15474517.
