Melanotan II (MT-II)
Melanocortin receptor agonist · regulated research peptide
Overview
Melanotan II (MT-II) is a synthetic cyclic heptapeptide analog of α-MSH developed at the University of Arizona in the 1980s. The molecule is a non-selective agonist at multiple melanocortin receptors (MC1R, MC3R, MC4R, MC5R), and the broad receptor profile is what produces both the studied pigmentation effects (via MC1R on melanocytes) and the studied sexual-function effects (via MC4R in CNS). The cyclic structure, a lactam bridge between Lys10 and Asp5 of the parent α-MSH sequence, provides both protease resistance and a constrained active conformation that increases receptor binding affinity relative to the linear parent peptide. Lyochem supplies Melanotan II as a lyophilized powder at ≥99.0% HPLC purity. The cyclized structure requires careful synthesis and the analytical packet includes mass spec confirming the cyclic mass (1024.18 Da theoretical, -18 Da relative to the linear precursor due to the lactam-forming dehydration). MT-II is heavily regulated in major jurisdictions including the UK, Australia, EU markets, and Canada, and banned for direct human consumption in many; the product is supplied as a research material only and is not intended or sold for any use that would constitute human administration in jurisdictions where it is prohibited.
Who buys this, and why
Other research peptides in this category — Melanotan-1, Melanotan-2, PT-141, ACE-031, Adipotide-FTTP, EPO, HCG, HMG — ship to research labs studying topics outside the GH / cognitive / immune / mitochondrial / repair / longevity / Khavinson clusters. Each peptide has its own analytical-packet emphasis (e.g. glycoprotein bioassay in IU/mg for HCG; cyclised-form confirmation for oxytocin) noted in the per-product CoA scope.
Primary buyer fit: academic and contract research laboratories.
Specifications
- CAS
- 121062-08-6
- Purity (HPLC)
- ≥ 99.0%
- Common vial sizes
- 10 mg
- MOQ
- On request
- Lead time
- 10–18 days
- Storage
- -20°C, protect from light
Documentation available on request
- Lot-specific Certificate of Analysis (CoA)
- RP-HPLC chromatogram with peak integration
- ESI-MS identity confirmation (±0.5 Da)
- Sequence verification by LC-MS/MS
- Water content by Karl Fischer
- SDS / MSDS
- Counter-ion analysis (where applicable)
- Solubility / reconstitution guidance
- Bacterial endotoxin (LAL) on request — in vivo workflows
Regulatory note
Heavily regulated; banned for human use in multiple jurisdictions including UK, Australia, and several EU markets. Sold only to qualified buyers with appropriate licensing in their jurisdiction for legitimate research use. Order requires compliance review.
Frequently asked questions
How does Melanotan II differ from Melanotan I (Afamelanotide)?▾
Both are α-MSH analogs designed to drive melanocortin-receptor signaling, but they differ structurally and pharmacologically. Melanotan I (Afamelanotide) is a linear 13-amino-acid α-MSH analog with [Nle4, D-Phe7] substitutions that provide protease resistance, it is selective for MC1R (the pigmentation receptor) over the other melanocortin receptors, which is why it became approvable as a prescription drug for erythropoietic protoporphyria. Melanotan II is a cyclic 7-residue analog with broader (non-selective) activity across MC1R, MC3R, MC4R, and MC5R, the broader receptor profile drives both pigmentation effects and the off-target effects (CNS, cardiovascular, sexual-function) that make MT-II more heavily regulated than MT-I in most jurisdictions.
Why is MT-II's cyclic structure analytically important to confirm?▾
Melanotan II's biological activity depends on the cyclic conformation produced by a lactam bridge between Lys10 and Asp5 of the parent α-MSH sequence. The cyclic and linear (uncyclized) forms differ by 18 Da in mass (the water lost during lactam formation) and elute at substantially different RP-HPLC retention times. The linear precursor has dramatically reduced receptor-binding affinity compared with the cyclic form, so analytical confirmation that the released-batch material is the cyclized form is essential. The COA should explicitly report mass spec confirming the cyclized mass (≈1024 Da theoretical), if the dominant species elutes at the linear-precursor mass, the cyclization step did not complete and the material lacks the defining MT-II pharmacology.
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