Melanotan 1 vs Melanotan 2
One of these two is a licensed European medicine with an approved indication. The other is an unlicensed research compound. They are also built differently — one is a ring, the other a chain.
The regulatory difference comes first
Melanotan I is afamelanotide, and afamelanotide is a licensed medicine. It holds European marketing authorisation under the name Scenesse, indicated for erythropoietic protoporphyria — a rare condition causing severe light sensitivity. It is a prescription medicine with an approved indication, a Summary of Product Characteristics and a regulator maintaining both.
Melanotan II holds no marketing authorisation anywhere. It is an unlicensed research compound, which is what we supply it as.
That difference is larger than any structural one, and it is the difference most comparisons of these two leave out entirely. See are peptides legal in the UK for how the categories work.
Linear and cyclic
Both are analogues of α-melanocyte-stimulating hormone — α-MSH — but they are built on different plans.
Afamelanotide is linear: a straight-chain analogue of the α-MSH sequence. Melanotan II is cyclic: the chain is closed into a ring. Cyclising a peptide constrains its shape, and a constrained shape changes which receptors it fits.
Melanotan II's molecular formula is C50H69N15O9, molecular weight 1,024.2, CAS 121062-08-6, from PubChem CID 92432. It is also listed as Melanotan-II and MT-II.
Receptor selectivity, which follows from the shape
There are five melanocortin receptors — MC1R through MC5R — and they do unrelated things in different tissues. How selective a compound is across that family is one of the most consequential things about it.
Melanotan II is not selective across them. That is not an accusation, it is what the compound has been used for in the literature: a 2022 paper in the Journal of Medicinal Chemistry describes using Melanotan-II as a scaffold to discover functionally selective human melanocortin receptor agonists (PMID 35188390). You start from a non-selective compound when selectivity is the thing you are trying to engineer in.
Afamelanotide is the more MC1R-directed of the two, and MC1R is the receptor its approved indication depends on.
Side by side
| Melanotan I | Melanotan II | |
|---|---|---|
| Also known as | Afamelanotide; Scenesse | Melanotan-II, MT-II |
| Structure | Linear α-MSH analogue | Cyclic α-MSH analogue |
| Receptor selectivity | More MC1R-directed | Non-selective across the melanocortin receptors |
| Molecular weight | Not held in our file | 1,024.2 |
| CAS | Not held in our file | 121062-08-6 |
| Regulatory status | Licensed medicine in the EU, for erythropoietic protoporphyria | No marketing authorisation anywhere |
| Supplied by Peptiq | No | Yes — nasal spray, research use only |
Afamelanotide, or Melanotan I is not in the Peptiq range. It is described here because the comparison is asked for, and the description is limited to published chemistry and regulatory status — we do not hold an evidence file on a compound we do not supply.
What the Melanotan II literature consists of
It is a mixed record and worth describing accurately rather than as a block.
The medicinal-chemistry work is the scaffold paper above (PMID 35188390). A 2023 paper in Biomedicine & Pharmacotherapy reported on memory impairment induced by a short-term high-fat diet in an animal model (PMID 37478579).
The third entry is a different kind of paper altogether: a 2021 qualitative study in Dermatology analysing online discussion forums (PMID 34464955). That is a study of what people wrote on the internet, not a study of the compound. It is indexed on PubMed and it belongs in the record, but it is evidence about discussion and we are not going to let a forum analysis stand in for pharmacology.
Format
We stock Melanotan 2 as a ready-to-use nasal spray rather than a vial, so there is no reconstitution step. Everything else in the range offered that way is listed on the nasal sprays page.
Supply note. Peptiq supplies research compounds for laboratory research use only. We are not a pharmacy and we do not supply licensed medicines. Where a licensed medicine is named on this page it is named to draw a distinction, not because we sell it, and nothing here is guidance on use.
Frequently asked questions
What is the difference between Melanotan 1 and Melanotan 2?
Melanotan I is afamelanotide, a linear α-MSH analogue that holds European marketing authorisation as Scenesse for erythropoietic protoporphyria. Melanotan II is a cyclic α-MSH analogue with no marketing authorisation anywhere, and it is non-selective across the melanocortin receptors.
Is Melanotan 1 a licensed medicine?
Afamelanotide is licensed in the EU as Scenesse, for erythropoietic protoporphyria. That authorisation belongs to that licensed product. Afamelanotide is not in the Peptiq range.
Which one do you supply?
Melanotan 2 only, as a ready-to-use nasal spray, as an unlicensed research compound for laboratory research use only.