Melanotan II
Also known as Melanotan 2, MT-II, MT2
Melanotan II is a synthetic cyclic analog of α-MSH studied as a non-selective melanocortin-receptor agonist. A research-use profile: structure, receptor family, and handling — no use guidance.
Melanotan II is a laboratory-synthesized peptide built as a cyclic analog of the natural hormone α-melanocyte-stimulating hormone. In the research literature it is characterized simply and precisely: it is an agonist at melanocortin receptors. That receptor pharmacology is the whole of what this page addresses.
Melanotan II carries a large amount of non-scientific baggage online. We are deliberately setting all of that aside. This is a research compound, and the only responsible framing is the one the chemistry supports — its structure, the receptor family it engages, and how it is handled in a lab. No cosmetic, physiological, or use claims of any kind appear here.
A synthetic cyclic heptapeptide analog of α-melanocyte-stimulating hormone (α-MSH). It is ring-closed through a lactam bridge and includes non-proteinogenic residues, so it is described by its analog relationship to α-MSH rather than a linear proteinogenic sequence.
A cyclic α-MSH analog
The design idea behind Melanotan II is stabilization. Native α-MSH is a linear peptide that is rapidly degraded; Melanotan II is a shortened, cyclized version engineered to be more resistant to breakdown while retaining recognition at melanocortin receptors. The ring is closed by a lactam bridge, and the sequence substitutes several non-standard residues for the natural ones — which is why it is described as an analog rather than a fragment.
That cyclic, non-proteinogenic construction is also why a plain one-letter amino-acid sequence is not a faithful representation of the molecule. Researchers identify it by its α-MSH analog relationship and its mass.
The melanocortin receptor family it engages
Melanotan II is studied as a non-selective agonist across the melanocortin receptor family — the five G-protein-coupled receptors MC1R through MC5R. Its lack of strong selectivity is itself a research characteristic: it engages several members of the family rather than one, which distinguishes it from more selective melanocortin tools.
It is the structural parent of PT-141 (bremelanotide), the des-amide metabolite of the same core. The two are routinely discussed together because they share this cyclic scaffold and overlap in receptor engagement.
Reading a Melanotan II certificate of analysis
As a small, defined cyclic peptide, Melanotan II should present a mass-spectrometry value consistent with its structure and a dominant single HPLC peak. A stated purity figure means little without the method behind it and a batch identifier to tie it to a specific lot. Verify any lot against its own certificate by batch number.
These are research areas the compound is associated with in the literature — not medical claims or intended uses.
Handling & storage
Supplied lyophilized. Kept sealed and cold; in research settings it is reconstituted with bacteriostatic water only when a protocol requires it, then refrigerated. Handle strictly per accepted laboratory practice.
Verify a certificate by lot →Common questions
A synthetic cyclic peptide analog of α-MSH, studied as a non-selective agonist at melanocortin receptors. It is ring-closed and contains non-standard residues.
Melanotan II is the structural parent; PT-141 (bremelanotide) is its des-amide metabolite. They share the same cyclic core, which is why they are discussed together.
It is a cyclic molecule with non-proteinogenic residues and a lactam bridge, so a plain one-letter sequence would not represent it accurately. It is identified by its α-MSH analog relationship and mass.
This monograph is a research-use reference. It describes composition and the contexts in which the compound has been studied — it is not medical advice, a description of effects, or a recommendation for use. Sold strictly for laboratory and research use; not for human or animal consumption.