alpha-melanocyte-stimulating hormone alpha-melanocyte-stimulating hormone α-melanocyte-stimulating hormone (α-msh) is an endogenous peptide hormone and neuropeptide 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, sexual activity, and protection against ischemia and reperfusion injury. α-melanocyte-stimulating hormone names iupac name n-acetyl-l-seryl-l-tyrosyl-l-seryl-l-methionyl-l-α-glutamyl-l-histidyl-l-phenylalanyl-l-arginyl-l-tryptophylglycyl-l-lysyl-l-prolyl-l-valinamide other names alpha-msh, α-melanocortin, α-melanotropin, α-intermedin; ac-ser-tyr-ser-met-glu-his-phe-arg-trp-gly-lys-pro-val-nh2 identifiers cas number 581-05-5 y chembl chembl214332 y chemspider 17288804 y pubchem cid 16132636 unii ovf025la77 y comptox dashboard (epa) dtxsid50226430 inchi inchi=1s/c77h109n21o19s/c1-42(2)64(65(79)106)97-75(116)61-20-13-30-98(61)76(117)54(18-10-11-28-78)88-62(103)38-85-66(107)57(34-46-36-84-50-17-9-8-16-49(46)50)94-67(108)51(19-12-29-83-77(80)81)89-70(111)55(32-44-14-6-5-7-15-44)92-72(113)58(35-47-37-82-41-86-47)95-68(109)52(25-26-63(104)105)90-69(110)53(27-31-118-4)91-74(115)60(40-100)96-71(112)56(33-45-21-23-48(102)24-22-45)93-73(114)59(39-99)87-43(3)101/h5-9,14-17,21-24,36-37,41-42,51-61,64,84,99-100,102h,10-13,18-20,25-35,38-40,78h2,1-4h3,(h2,79,106)(h,82,86)(h,85,107)(h,87,101)(h,88,103)(h,89,111)(h,90,110)(h,91,115)(h,92,113)(h,93,114)(h,94,108)(h,95,109)(h,96,112)(h,97,116)(h,104,105)(h4,80,81,83) ykey: whnfprlddsxqcl-uhfffaoysa-n yinchi=1/c77h109n21o19s/c1-42(2)64(65(79)106)97-75(116)61-20-13-30-98(61)76(117)54(18-10-11-28-78)88-62(103)38-85-66(107)57(34-46-36-84-50-17-9-8-16-49(46)50)94-67(108)51(19-12-29-83-77(80)81)89-70(111)55(32-44-14-6-5-7-15-44)92-72(113)58(35-47-37-82-41-86-47)95-68(109)52(25-26-63(104)105)90-69(110)53(27-31-118-4)91-74(115)60(40-100)96-71(112)56(33-45-21-23-48(102)24-22-45)93-73(114)59(39-99)87-43(3)101/h5-9,14-17,21-24,36-37,41-42,51-61,64,84,99-100,102h,10-13,18-20,25-35,38-40,78h2,1-4h3,(h2,79,106)(h,82,86)(h,85,107)(h,87,101)(h,88,103)(h,89,111)(h,90,110)(h,91,115)(h,92,113)(h,93,114)(h,94,108)(h,95,109)(h,96,112)(h,97,116)(h,104,105)(h4,80,81,83)key: whnfprlddsxqcl-uhfffaoyap properties chemical formula c77h109n21o19s molar mass 1664.884 g/mol except where otherwise noted, data are given for materials in their standard state (at 25 °c , 100 kpa). n verify (what is yn ?) infobox references α-msh is a non-selective full agonist of the melanocortin receptors mc1 (ki = 0.230 nm), mc3 (ki = 31.5 nm), mc4 (ki = 900 nm), and mc5 (ki = 7160 nm), 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 has been approved as a treatment to reduce photosensitivity in erythropoietic protoporphyria in the united states. bremelanotide, another analogue of α-msh, is available in the united states not as a photoprotective agent, but for the treatment of hypoactive sexual desire disorder in premenopausal women. all of these drugs have significantly greater potencies than α-msh, along with improved pharmacokinetics and distinctive selectivity profiles.