MC1R Agonism & Melanogenesis Stimulation
Afamelanotide (Melanotan-I)
Last reviewed: August 2026
MT1 (Melanotan I, clinically known as afamelanotide) is a synthetic version of a hormone your body naturally produces called alpha-MSH. This hormone is part of your skin's built-in sun protection system — it's what triggers your skin to tan in response to UV exposure.
MT1 works by activating a receptor on melanocytes (the cells that produce skin pigment) called MC1R. When this receptor is activated, it triggers a chain reaction that increases production of eumelanin — the dark, protective form of melanin. Crucially, MT1 can do this without requiring UV exposure first. It's essentially activating the tanning pathway directly.
MT1 is the only peptide in this guide that has received full regulatory approval — it's sold in the EU as Scenesse® for a rare genetic condition called erythropoietic protoporphyria (EPP), where patients experience extreme pain from even brief sun exposure. This means MT1 has completed Phase III clinical trials and has a well-characterized human safety profile, which is rare in the peptide research space.
MT1 stands apart from most research peptides because it has genuine clinical validation behind it. The EU-approved formulation is a subcutaneous implant; Purgo Labs supplies the lyophilized powder format strictly for laboratory research use. The clinical data provides a strong mechanistic foundation for researchers studying melanocortin biology.
Melanotan I (MT1), clinically known as afamelanotide, is a synthetic analog of alpha-melanocyte-stimulating hormone (α-MSH), a naturally occurring neuropeptide derived from proopiomelanocortin (POMC). Developed initially at the University of Arizona, MT1 was engineered to be a more potent and metabolically stable version of α-MSH, with a half-life of approximately 1.5 hours compared to the native hormone's minutes-long duration.
MT1 is the only melanocortin receptor agonist to have received regulatory approval — it is approved in the European Union under the brand name Scenesse® for the prevention of phototoxicity in adults with erythropoietic protoporphyria (EPP), a rare genetic disorder causing extreme light sensitivity. This clinical validation distinguishes MT1 from most research peptides and provides a robust human safety and efficacy dataset.
Afamelanotide is a 13-amino-acid linear peptide with the sequence Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2. Key structural modifications compared to native α-MSH include: substitution of Met⁴ with norleucine (Nle) to prevent oxidative degradation, replacement of Phe⁷ with D-Phe to increase receptor binding affinity and metabolic stability, and N-terminal acetylation with C-terminal amidation to further resist enzymatic degradation.
These modifications collectively extend the biological half-life from approximately 2–3 minutes (native α-MSH) to approximately 1.5 hours, while also increasing potency at the melanocortin-1 receptor (MC1R) by approximately 100-fold compared to the native sequence.
MT-1 reduces UV-induced skin damage by activating MC1R receptors in melanocytes, increasing melanin production before sun exposure.
MT1 functions as a potent agonist of the melanocortin-1 receptor (MC1R), a G-protein coupled receptor expressed predominantly on melanocytes in the skin. Upon binding to MC1R, MT1 activates the Gαs protein, stimulating adenylyl cyclase and increasing intracellular cyclic AMP (cAMP) levels. Elevated cAMP activates protein kinase A (PKA), which phosphorylates the transcription factor CREB (cAMP response element-binding protein).
Phosphorylated CREB activates the microphthalmia-associated transcription factor (MITF), the master regulator of melanocyte biology. MITF drives expression of tyrosinase, tyrosinase-related protein-1 (TRP-1), and TRP-2 — the key enzymes of the melanogenesis pathway — resulting in increased eumelanin production and enhanced photoprotection.
Binds MC1R on melanocytes, activating adenylyl cyclase → cAMP → PKA cascade that drives melanogenesis transcription factors.
PKA phosphorylates CREB, which activates MITF — the master regulator of melanocyte biology and eumelanin synthesis.
MITF drives expression of tyrosinase, TRP-1, and TRP-2, the enzymatic machinery of eumelanin production.
MC1R activation suppresses NF-κB-mediated inflammatory signaling, providing secondary anti-inflammatory effects.
Each outcome rated by the highest level of evidence available. Tiers follow our 5-tier methodology.
Study counts reflect peer-reviewed publications in the evidence database below. "Theoretical" outcomes have mechanistic rationale only. Learn about our evidence tiers →
Peer-reviewed literature supporting the research profile of MT1
The following peer-reviewed studies form the primary evidence base for MT1's research profile. All references are sourced from PubMed, NCBI, and peer-reviewed scientific journals. Published research is available through PubMed, NCBI, and peer-reviewed biomedical journals.
Hadley ME, Dorr RT. Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialization. Peptides. 2006.PMID: 16412534
Historical overview of melanocortin peptide development including Melanotan I clinical studies.
Levine N, et al. Induction of skin tanning by subcutaneous administration of a potent synthetic melanotropin. JAMA. 1991.PMID: 1658407
First human clinical demonstration of Melanotan I-induced skin pigmentation via MC1R activation.
Dorr RT, et al. Effects of a superpotent melanotropic peptide in combination with solar UV radiation on tanning of the skin in human volunteers. Archives of Dermatology. 2004.PMID: 15262693
Confirmed photoprotective and tanning effects of Melanotan I in controlled UV exposure studies.
Skin & Anti-Aging Research
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Approved drug (Scenesse implant, EPP) — profile from its trials and label; research vials are not the implant
Afamelanotide is approved as a subcutaneous implant for erythropoietic protoporphyria, so controlled human data exist: implant-site reactions, nausea, headache and darkening of existing moles are the documented effects. Research-grade 'MT1' powder is an injectable of unverified identity, not the implant, and has no trial data of its own.
Research-use information only. Research-grade Melanotan I is not an approved medicine; where trial or label figures appear below they belong to the pharmaceutical product studied, not to any research vial. This section does not give dosing or medical advice.
Every rate carries its source. Where no source exists, no rate is printed.
| Effect | Rate (sourced) | Detail | Source |
|---|---|---|---|
| Implant-site reactions | not quantified | Most common in the phase 3 trials. | Langendonk et al. 2015 |
| Nausea, headache, oropharyngeal pain | not quantified | Reported more often than placebo. | Langendonk et al. 2015; Scenesse label |
| Darkening of naevi and new naevi | not quantified | Expected pharmacology of MC1R agonism; the label recommends skin examinations. | Scenesse label |
Regulatory status: FDA-approved as Scenesse (2019) for EPP. Research-grade MT1 is not approved for any use.
Afamelanotide is MC1R-selective and has approval data; melanotan II is non-selective, unapproved, and its literature is case reports. That is a real difference in what is known, not proof of safety for research-grade MT1 vials.
Side-effect section last reviewed 2026-09-12. Moved from the standalone side-effects page on 10 October 2026; text unchanged.
Afamelanotide (Scenesse®) is the only melanocortin agonist with FDA and EMA regulatory approval. Its approved indication is strictly limited to prevention of phototoxicity in adults with erythropoietic protoporphyria (EPP), a rare genetic disorder. This evidence base does NOT support use for tanning, cosmetic melanogenesis, or any other indication. MT1 and MT2 are distinct compounds and must not be treated as interchangeable.
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