alpha-Melanocyte-stimulating hormone

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α-Melanocyte-stimulating hormone
Identifiers
CAS number 581-05-5 N
PubChem 16132636
ChemSpider 17289286 YesY
ChEMBL CHEMBL385886 YesY
Properties
Molecular formula C77H109N21O19S
Molar mass 1664.884 g/mol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

α-Melanocyte-stimulating hormone (alpha-MSH; α-MSH), also known as alpha-melanotropin, alpha-melanocortin, or alpha-intermedin, is a naturally occurring endogenous peptide hormone of the melanocortin family, with a tridecapeptide structure and the amino acid sequence Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2. It is the most important of the melanocyte-stimulating hormones (MSHs; also known as melanotropins) in stimulating melanogenesis, a process that in mammals (including humans) is responsible for pigmentation primarily of the hair and skin. It also plays a role in feeding behavior, energy homeostasis, and sexual activity.

α-MSH is a nonselective agonist of the melanocortin receptors MC1, MC3, MC4 and MC5, but not MC2, [which is exclusive for adrenocorticotropic hormone (ACTH)]. Activation of the MC1 receptor is responsible for its effect on pigmentation, whereas its regulation of appetite, metabolism, and sexual behavior is mediated through both the MC3 and MC4 receptors.

It is generated as a proteolyic cleavage product from ACTH (1-13), which is in turn a cleavage product of proopiomelanocortin (POMC).

A few synthetic analogues of α-MSH have been investigated as medicinal drugs due to their photoprotective effects against ultraviolet (UV) radiation from the sun. They include afamelanotide (melanotan) and melanotan II, the former of which being in phase-III clinical trials in the United States. Bremelanotide, another analogue of α-MSH, is currently under development not as a photoprotective agent, but instead for the treatment of sexual dysfunction. All of these drugs have significantly greater potencies than α-MSH, along with improved pharmacokinetics and distinctive selectivity profiles.

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