Melanotan-1 vs Melanotan-2

Melanotan-1

Melanotan 1, also designated Afamelanotide, is a linear synthetic tridecapeptide analogue of alpha-melanocyte-stimulating hormone (alpha-MSH) with the substitution of Nle at position 4 and D-Phe at position 7, conferring enhanced receptor binding affinity and metabolic stability. Melanotan 1 selectively activates melanocortin-1 receptor (MC1R), the primary receptor responsible for melanogenesis in epidermal melanocytes. MC1R activation triggers adenylyl cyclase-mediated cAMP elevation, which upregulates microphthalmia-associated transcription factor (MITF) and downstream eumelanin synthesis enzymes. Research published in the British Journal of Dermatology by Barnetson et al. (2006) demonstrated that Afamelanotide produced significant increases in melanin density without UV exposure in fair-skinned individuals, conferring a measurable photoprotective effect. Harms et al. in Photochemistry and Photobiology showed that Melanotan 1-induced eumelanin production provided DNA damage protection equivalent to moderate constitutive pigmentation. Studies in erythropoietic protoporphyria (EPP) patients published in the New England Journal of Medicine (Langendonk et al., 2015) demonstrated that Afamelanotide significantly increased pain-free time in sunlight. Compared to Melanotan 2, which is a cyclic heptapeptide acting non-selectively across MC1R through MC5R, Melanotan 1 is more selective for MC1R and therefore produces fewer off-target effects. Melanotan 2 additionally activates MC4R (associated with appetite and arousal), while Melanotan 1's selectivity makes it more suitable for focused pigmentation research. Store lyophilized Melanotan 1 at -20°C, protected from light. Reconstitute with bacteriostatic water and store at 2-8°C, using within 4 weeks. This peptide is studied by dermatologists, photobiologists, and researchers investigating melanocortin receptor pharmacology and photoprotective strategies.

Melanotan-2

Melanotan 2 is a cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone (alpha-MSH) with the sequence Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-NH2. Its cyclic structure confers enhanced metabolic stability and broad melanocortin receptor affinity, activating MC1R (pigmentation), MC3R (energy homeostasis), MC4R (sexual function and appetite), and MC5R (exocrine gland function). This multi-receptor activity profile distinguishes it from more selective melanocortin analogues and accounts for its diverse range of biological effects observed in research settings. Originally developed at the University of Arizona by Hruby and colleagues, Melanotan 2 was first characterized in studies published in the Journal of Medicinal Chemistry (1989), where its potent melanotropic activity was established. Subsequent research by Dorr et al. in Archives of Dermatological Research demonstrated dose-dependent increases in skin pigmentation without UV exposure. Studies in Neuroscience by Wessells et al. documented that MC4R activation by Melanotan 2 produced pro-erectile effects in animal models, findings that later informed the development of PT-141 (Bremelanotide), which was derived directly from Melanotan 2 as a more targeted therapeutic candidate. Compared to Melanotan 1 (Afamelanotide), which is linear and MC1R-selective, Melanotan 2's cyclic structure gives it broader receptor coverage and higher potency per mole. However, this reduced selectivity means research must account for concurrent effects across multiple melanocortin pathways. Both peptides share the Nle4/D-Phe7 substitutions that distinguish them from native alpha-MSH. Lyophilized Melanotan 2 should be stored at -20°C, protected from light. Reconstitute with bacteriostatic water and store at 2-8°C, using within 4 weeks. Researchers in dermatology, sexual medicine, neuropharmacology, and melanocortin receptor biology are the primary investigators of this compound.

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