Melanotan 1

Melanotan 1 (MT-1), also known as afamelanotide, is a synthetic tridecapeptide analog of alpha-melanocyte-stimulating hormone (α-MSH). It was developed at the University of Arizona by Hruby and Hadley and contains two key modifications from native α-MSH: a norleucine substitution at position 4 (replacing methionine) and a D-phenylalanine substitution at position 7 (replacing L-phenylalanine). These changes create NDP-α-MSH (Nle4, D-Phe7-α-MSH), which is approximately 100-1000 times more potent than native α-MSH at the MC1R receptor and is resistant to enzymatic degradation. Afamelanotide was approved by the European Medicines Agency in 2014 under the brand name Scenesse for the prevention of phototoxicity in patients with erythropoietic protoporphyria. MT-1 is a relatively selective MC1R agonist compared to Melanotan 2, which has broader melanocortin receptor activity.

Melanotan 1 has been investigated for its potent and selective agonism of the melanocortin 1 receptor (MC1R), a Gs-coupled GPCR expressed on melanocytes and other cell types. Researchers observed that MC1R activation by MT-1 stimulates adenylyl cyclase, increasing intracellular cAMP, which activates CREB (cAMP response element binding protein) and induces MITF (microphthalmia-associated transcription factor) expression. MITF drives transcription of melanogenic enzymes including tyrosinase, TRP-1, and TRP-2, promoting eumelanin (brown/black pigment) synthesis. Studies suggest that eumelanin production provides photoprotection through UV absorption and reactive oxygen species scavenging. MT-1’s selectivity for MC1R over MC3R, MC4R, and MC5R distinguishes it from Melanotan 2, which has broader receptor activity. In clinical studies, researchers observed that MT-1 administration was associated with increased melanin density without UV exposure, and enhanced the melanogenic response to subsequent UV exposure.

MC1R Pharmacology

Hruby et al. (1995) described the design and characterization of NDP-α-MSH (Melanotan 1), demonstrating its enhanced potency, stability, and MC1R selectivity compared to native α-MSH [1].

Clinical Photoprotection

Langendonk et al. (2015) reported results from a Phase 3 clinical trial of afamelanotide in erythropoietic protoporphyria, demonstrating increased time to phototoxicity symptoms and supporting regulatory approval [2].

Melanogenesis

Barnetson et al. (2006) investigated afamelanotide in a clinical study and observed increased melanin density and skin darkening, with enhanced photoprotection against UV-induced erythema [3].