What Melanotan II is
Melanotan II (MT-II) is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone (α-MSH): Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2. It was developed at the University of Arizona in the 1980s, when researchers there were synthesizing α-MSH analogues as candidate sunless tanning agents. The lactam ring and D-phenylalanine make it far more resistant to breakdown than native α-MSH.
Receptor activity and research areas
MT-II is a non-selective agonist at four melanocortin receptors. MC1R activation drives melanogenesis (pigmentation), the original reason for its development. MC4R is the receptor most often linked in the literature to its effects on sexual behaviour and on appetite and energy balance; MC3R and MC5R are also bound.
Published work reflects that spread: small human studies of erectile response from the University of Arizona group (Wessells et al., 2000), and rodent studies of insulin sensitivity (Banno et al., 2004), neuropeptide Y-driven feeding (Raposinho et al., 2003) and thermogenesis (McMillan et al., 2021). Because it hits several receptors at once, MT-II is mainly used as a broad melanocortin tool compound.
Related compounds: afamelanotide and bremelanotide
Two approved drugs came out of the same research line. Afamelanotide (originally melanotan I) is a linear analogue that favours MC1R; it was FDA-approved in 2019 as Scenesse. Bremelanotide differs from MT-II mainly by a free carboxylic acid where MT-II has a C-terminal amide, and was FDA-approved in 2019 as Vyleesi. Bremelanotide is the compound sold for research as PT-141; see also MT-1.
Regulatory status (October 2026)
MT-II itself has never been approved anywhere. Medicines regulators in Norway (2007), Denmark and the United Kingdom (2008), the United States (2009) and Ireland (2009) have issued warnings about unlicensed products sold for human use. FDA’s Pharmacy Compounding Advisory Committee is expected to review Melanotan II at a meeting before the end of February 2027.
Common questions
What is the difference between MT-2 and PT-141?
PT-141 (bremelanotide) is closely related to MT-II, differing mainly by a C-terminal carboxylic acid instead of an amide. Bremelanotide is FDA-approved as Vyleesi; MT-II is not approved anywhere.
Which receptors does Melanotan II act on?
It is a non-selective agonist of the MC1, MC3, MC4 and MC5 melanocortin receptors.
Who developed Melanotan II?
Researchers at the University of Arizona in the 1980s, while developing alpha-MSH analogues as sunless tanning agents.
Background sources
Chemistry & identity
| CAS Number | 121062-08-6 |
|---|---|
| Molecular Formula | C50H69N15O9 |
| Molecular Weight | 1024.2 g/mol |
| Residue Count | 7 |
| PubChem CID | 92432 |
Peptide sequence
XDHFRWK
Research context
Chemistry is for melanotan II free base (no PubChem record found for the acetate salt). PubChem synonym: Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2; X = Nle, residue 4 is D-Phe.
Selected research references
Published peer-reviewed literature on MT-2 (Melanotan 2 Acetate). Provided for research-context purposes only; Central Coast Peptides does not make claims about outcomes in humans.
- Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II
- The melanocortin agonist melanotan II increases insulin sensitivity in OLETF rats
- The melanocortin agonist Melanotan-II reduces the orexigenic and adipogenic effects of neuropeptide Y (NPY) but does not affect the NPY-driven suppressive effects on the gonadotropic and somatotropic axes in the male rat
- Melanotan II, a melanocortin agonist, partially rescues the impaired thermogenic capacity of pituitary adenylate cyclase-activating polypeptide deficient mice
Related lab guides
- How to read a peptide certificate of analysis (COA) · HPLC purity, mass spec identity and net peptide content
- How to store lyophilized peptides · Temperature, moisture and light
- Reconstitution calculator · Concentration and mg per 0.1 mL for any vial size
MT-2 (Melanotan 2 Acetate) for laboratory research
Central Coast Peptides supplies MT-2 (Melanotan 2 Acetate) as a lyophilized reference material with a third-party COA. Ships from California.
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