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Compound guide
Melanotan II: what the research covers
A cyclic lactam analogue of alpha-MSH that binds across the melanocortin receptor family rather than selectively. Why the lack of selectivity is the defining feature.
What Melanotan II is
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte stimulating hormone. The cyclisation — a lactam bridge between residues in the core sequence — constrains the molecule into a conformation that resists enzymatic degradation and increases receptor affinity relative to the native hormone.
Its defining property is that it is non-selective. Alpha-MSH signals through five melanocortin receptor subtypes with different tissue distributions and different functions: MC1R on melanocytes governs pigmentation, MC3R and MC4R are central and involved in energy balance and sexual behaviour, MC5R is exocrine. Melanotan II binds across that family. Melanotan I, by contrast, is MC1R-selective, and the Melanotan I versus II comparison sets out what follows from that difference.
What the literature examines
The pigmentation strand is the oldest: MC1R agonism drives the switch from phaeomelanin to eumelanin synthesis in melanocytes, and that is the pathway the original Arizona research programme was built around.
The central strands are the reason the compound remains of research interest. MC4R signalling in the hypothalamus is implicated in appetite regulation, and separately in the central component of sexual arousal — the observation that led directly to the development of PT-141, which is a metabolite of Melanotan II refined for MC4R selectivity and no longer studied for pigmentation at all.
Because the compound acts at several receptor families at once, effects reported in one system cannot be cleanly separated from activity in another without a selective comparator, which is the principal design difficulty in working with it. Published work is indexed on PubMed.
How Amino Club supplies it
Melanotan II is supplied lyophilised in sealed vials as Melanotan II and as a metered 15ml intranasal preparation, Melanotan II nasal spray. The MC1R-selective Melanotan I is listed alongside it.
Each batch is specified at 99% purity or better by HPLC with identity confirmed by mass spectrometry and released against the Certificate of Analysis carrying the batch number on the vial; the process is documented on the lab testing page. For a cyclic peptide, mass spectrometric confirmation matters more than usual: a linear sequence of identical composition will pass a crude mass check and is a different molecule with different receptor behaviour.
Reconstitution and storage notes are on the product page; solvents are under reconstitution supplies.
Related reading
Melanotan II sits in the skin and cosmetic group with GHK-Cu, AHK-Cu, SNAP-8 and glutathione, while the MC4R-selective PT-141 is grouped under sexual health. Comparison: Melanotan I versus Melanotan II.
Everything is indexed in the research library. Certificates and storage are covered on the FAQ.
Research use only
Melanotan II supplied by Amino Club is a laboratory reference material. It is not a medicine, not a cosmetic, not a supplement, and not for human or veterinary use, and no dosing guidance or administration protocol is provided. The full terms are in the research use policy.