Melanotan II
Cyclic heptapeptide melanocortin receptor agonist (non-selective)
Also known as MT-II, MT2, Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2
A cyclic analogue of α-MSH developed at the University of Arizona as a potent, non-selective melanocortin receptor agonist. Studied in pigmentation and sexual-function physiology; never approved as a medicine.
Technical information
Values are shown with their status. “Verified” means the value has been checked against a primary database such as PubChem.
- Classification
- Cyclic heptapeptide melanocortin receptor agonist (non-selective)
- CAS number
- 121062-08-6 Pending
- Molecular formula
- C50H69N15O9 Pending
- Molecular weight
- 1024.2 g/mol Pending
- Sequence / structure
- Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 (lactam-bridged) Pending
Some values are still being checked and should be treated as provisional until marked verified.
How this compound is tested
Cyclic peptide: LC-MS identity (lactam bridge reflected in mass) and HPLC purity. Linear (uncyclised) impurities are a known related substance class.
Research background
Melanotan II was synthesised in the 1980s–90s in the course of work on α-MSH analogues for sunless tanning. It activates MC1, MC3, MC4 and MC5 receptors. Early clinical pharmacology (Dorr et al., 1996) reported pigmentation and, unexpectedly, erectile responses, which led to the development of the MC4-selective bremelanotide (PT-141). Melanotan II has been widely sold illicitly as a tanning product; regulators including the UK MHRA have issued warnings about unlicensed products.
Mechanisms investigated in published research
These are the mechanisms examined in the cited literature. Describing them is not a claim that the compound produces any effect in humans.
- Non-selective melanocortin receptor agonism (MC1R: pigmentation; MC3R/MC4R: energy balance, sexual function; MC5R: exocrine function).
- Lactam cyclisation confers stability and potency relative to linear α-MSH.
Summary of evidence
Laboratory and animal findings are kept separate from human clinical evidence.
Preclinical findings
Receptor pharmacology and pigmentation studies in cells and animals; rodent studies of feeding and sexual behaviour.
Human clinical evidence
1 citedA pilot phase 1 study (Dorr et al., 1996) in healthy volunteers reported pigmentation and side effects including nausea and erections. No further regulated development; no approved medicine. Adverse events have been reported with unlicensed products in the literature and by regulators.
Limitations and open questions
- No controlled efficacy or long-term safety data.
- Regulatory warnings concern unlicensed products; this website does not supply products for human use.
- Melanocortin agonists are listed by WADA.
Scientific references
Publications cited on this page. Links open the publisher or PubMed record.
[1]Dorr RT, Lines R, Levine N, et al.. Evaluation of Melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sciences (1996).
Human clinical Citation pendingSmall phase 1 pilot in healthy volunteers.
Research use only
Melanotan II is described here for laboratory research. It is not approved for human or veterinary use unless a regulator has said otherwise, and nothing on this page is medical advice or guidance on administration. A disclaimer does not by itself make any activity lawful. Full disclaimer.
Contact options
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Cyclic heptapeptide melanocortin receptor agonist (MC4R-preferring)
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