Melanotan II research explained
What Melanotan II is
Melanotan II (MT-2, MT-II) is a synthetic cyclic peptide of seven amino acids. Its commonly reported structure is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, and its molecular weight is about 1024 Da. It was designed in the late 1980s at the University of Arizona by the groups of Victor Hruby and Mac Hadley as a shortened, ring-closed analogue of alpha-melanocyte-stimulating hormone (alpha-MSH), the 13-residue hormone that signals to pigment cells.
Three design changes separate it from the natural hormone: a norleucine in place of methionine, a D-phenylalanine in place of L-phenylalanine, and a lactam bridge between aspartate and lysine that closes the ring. The ring makes the peptide resistant to enzymatic breakdown and locks it into a shape that binds melanocortin receptors.
"Melanotan 2 acetate" is the same peptide supplied as an acetate salt, which is the usual counter-ion for a synthetic peptide. It is not a different compound.
Receptor targets
Melanotan II is a non-selective melanocortin receptor agonist. The five receptors in that family have different distributions and roles, and the peptide binds four of them.
| Receptor | Main location | Melanotan II |
|---|---|---|
| MC1R | Melanocytes in skin | Agonist |
| MC2R | Adrenal cortex | Not bound |
| MC3R | Brain, some peripheral tissue | Agonist |
| MC4R | Brain, hypothalamus | Agonist |
| MC5R | Exocrine glands | Agonist |
The lack of selectivity is the defining pharmacological fact. Afamelanotide (Melanotan I) is a linear analogue with greater MC1R preference, and the two should not be treated as interchangeable. The differences are set out in Melanotan I vs Melanotan II.
Development history and regulatory status
Melanotan II entered early clinical studies in the 1990s. The cited regulator notices warn about unregulated melanotan products. Its deamidated metabolite was later developed separately as bremelanotide (PT-141), which did reach licensure in the United States as Vyleesi.
Melanotan II itself is not a licensed medicine in the UK, the EU, the United States or Australia. The MHRA has issued public warnings about unlicensed melanotan products sold for human use since 2008. The catalogue item here is the Melanotan II 10mg research vial, supplied as lyophilised powder for in-vitro work only. Check the COA library for publication status; no EPS batch report is currently available.
Evidence tiers
| Statement | Evidence tier |
|---|---|
| Binds MC1R, MC3R, MC4R and MC5R | In vitro, demonstrated |
| Resistant to enzymatic degradation compared with alpha-MSH | In vitro, demonstrated |
| Effects in rodents on pigmentation and other melanocortin pathways | Animal |
| Human effects | Small early studies and case reports only |
Reports of adverse events in people who used unlicensed products are collected in Melanotan II adverse effects. The earlier overview of the whole family is Melanotan I and Melanotan II: melanocortin receptor research.
EPS documentation
Use the research catalogue to check the exact name, labelled amount and format. The COA library publishes the original Janoshik reports selected for EPS, retaining the original report client name and any missing batch fields. Literature findings and another supplier's analytical results are not evidence about an EPS batch.