×10 · 10-vial kitMelanotan II
Also known as Melanotan 2 and MT-2. Lyophilized, vacuum-sealed, 10-vial kit.
- CAS
- 121062-08-6
- Form
- Lyophilized powder
- Storage
- Frozen, in the dark
- Ships
- Kits by Dec 12, 2026
- Presale
- Ships within the US
- Pay by card or crypto
- All sales final
Melanotan II is a synthetic cyclic heptapeptide, also written Melanotan 2 or MT-II, built on residues 4 to 10 of alpha-melanocyte-stimulating hormone and closed into a ring by a lactam bridge. It was reported in 1989 by Al-Obeidi, Castrucci, Hadley and Hruby at the University of Arizona. In the literature it is a potent agonist at the melanocortin receptors that respond to alpha-MSH, and it has no approved drug application in the United States.
Supplied for laboratory research use only. Not for human or veterinary use, and not for diagnostic or therapeutic application.
Melanotan II: compound data
- Molecular formula
- C50H69N15O9
- Molecular weight
- 1,024.2 g/mol
- CAS number
- 121062-08-6
- PubChem
- CID 92432
- Form supplied
- Lyophilized powder, vacuum-sealed
- Concentration
- mg/mL and molarity calculator
Reference values from PubChem, the chemistry database of the US National Library of Medicine, for the compound as registered there.
About Melanotan II
Structure of Melanotan II
The peptide is Ac-Nle-cyclo(Asp-His-D-Phe-Arg-Trp-Lys)-NH2. In alpha-MSH numbering it is the 4 to 10 fragment with norleucine at position 4, aspartate at 5, D-phenylalanine at 7 and lysine at 10, acetylated at the amino terminus and amidated at the carboxyl terminus. The ring is a lactam formed between the aspartate side chain and the lysine side chain, which the 1989 paper counts as 23-membered. Because the bridge runs through side chains, the molecule keeps distinct ends. It differs from bremelanotide only at the carboxyl terminus, where bremelanotide has a free acid, and PubChem lists an acetate salt among its synonyms.
Where Melanotan II comes from
Al-Obeidi, Castrucci, Hadley and Hruby described the compound in the Journal of Medicinal Chemistry in 1989, in a paper whose design drew on molecular dynamics and on earlier potent analogs of alpha-MSH. They prepared seven cyclic lactam analogs of the 4 to 13 and 4 to 10 fragments, varying the bridging residues and closing the ring in solution or on a solid-phase support, and compared them with alpha-MSH in frog and lizard skin bioassays. Analogs with 23-membered rings were about 100-fold more potent than alpha-MSH in the lizard assay, and larger or smaller rings were less potent. The 4 to 10 member with aspartate and lysine is Melanotan II.
What Melanotan II binds
Melanotan II is an agonist at melanocortin receptors. A 1995 paper from the same group states that MC2R primarily recognizes ACTH peptides, while the other four receptors, MC1R, MC3R, MC4R and MC5R, all recognize alpha-MSH and potent agonists including this cyclic peptide. A 2011 review describes the family as five subtypes that signal mainly through intracellular cyclic AMP, with agouti and agouti-related protein as natural antagonists. The 1995 paper also showed that replacing D-phenylalanine with D-2-naphthylalanine in the same ring gives a compound that antagonizes MC4R and MC3R while remaining a full agonist at MC1R and MC5R.
Melanotan II in the research literature
The peptide appears in three kinds of study. The first is the isolated frog (Rana pipiens) and lizard (Anolis carolinensis) skin bioassays in which the series was originally ranked, which predate the cloning of the receptors. The second is recombinant receptor pharmacology: the 1995 paper examined analogs of this ring at cloned human and mouse melanocortin receptors and used it as the reference agonist scaffold. The third is conformational work, since the 1989 design was itself a probe of a molecular dynamics model of alpha-MSH. The Arizona authors framed such analogs as tools for determining what each receptor subtype does.
Regulatory status of Melanotan II
Melanotan II has no FDA-approved application. A 2016 FDA debarment order, 81 FR 79501, recounts that an August 30, 2007 warning letter told the company Melanocorp that the peptide as marketed was a new drug that could not enter interstate commerce without an approved application, and that later letters repeated that position and stated that unapproved new drugs do not qualify for export. FDA's compounding page also lists Melanotan II among withdrawn bulk substance nominations, citing possible immunogenicity from aggregation or peptide-related impurities. Here it is supplied as a reference reagent for in-vitro laboratory research only, not for human or veterinary diagnosis, treatment, or consumption.
Handling Melanotan II in the laboratory
Melanotan II arrives lyophilized in a vacuum-sealed vial. Keep the sealed vial frozen at -4 °F and protected from light, and let it reach room temperature before breaking the seal so that moisture does not condense on the powder. Once in solution, hold it at about 39 °F and use it within roughly four weeks; divide a stock into single-use aliquots instead of freezing and thawing one tube repeatedly. The ring contains one tryptophan, so solutions are best kept away from light. Its mass is within about one unit of bremelanotide, so identity checks by mass need enough resolution to separate the two.
Sources
- Melanotan II, PubChem CID 92432
- Potent and prolonged acting cyclic lactam analogues of alpha-melanotropin: design based on molecular dynamics (Al-Obeidi et al., J Med Chem, 1989)
- Cyclic lactam alpha-melanotropin analogues with bulky aromatic amino acids at position 7 show high antagonist potency and selectivity at specific melanocortin receptors (Hruby et al., J Med Chem, 1995)
- Structure, function and regulation of the melanocortin receptors (Yang, Eur J Pharmacol, 2011)
- Edward Manookian (Also Known as Ed Manning): Debarment Order, 81 FR 79501 (FDA, 2016)
- Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (FDA)
Research notes on Melanotan II
- Melanotan II: Melanocortin Receptor ResearchWhat Melanotan 2 is at the molecular level: the cyclic lactam structure, its melanocortin receptor profile, US regulatory record and lab handling.
Melanotan II: common questions
Is Melanotan 2 the same as Melanotan II?
Yes. Melanotan 2 is another name for Melanotan II, which is also written MT-2 (CAS 121062-08-6). It is the same compound, supplied here as a lyophilized powder for in-vitro laboratory research use only.
What is Melanotan II supplied as?
Melanotan II is supplied as a lyophilized (freeze-dried) powder in a vacuum-sealed vial, in 10 mg, for in-vitro laboratory research use only.
Is Melanotan II available as a 10-vial kit?
Yes. Melanotan II comes in a 10-vial kit: 10 mg for $157.50 ($15.75 per vial), presale prices. A kit is ten sealed vials of the same size, priced below ten single vials.
When do Melanotan II presale kits ship?
By Dec 12, 2026. Presale kits are 10% off. If we cannot ship by Dec 12, 2026, we tell you before that date and you can cancel for a full refund.
What is the CAS number of Melanotan II?
The CAS registry number of Melanotan II is 121062-08-6.
How should Melanotan II be stored?
Frozen at −4 °F and protected from light, from the day it arrives. Let the vial reach room temperature before breaking the seal; once reconstituted, stability holds for about four weeks refrigerated at 39 °F.
How fast does Melanotan II ship?
Presale kits ship from the United States by Dec 12, 2026, to US addresses. Sizes marked in stock ship within 1 business day of payment.
Is Melanotan II for human use?
No. It is supplied as a reference reagent for laboratory research use. Not for human or veterinary use, and not for diagnostic or therapeutic application.
What is the structure of Melanotan II?
Melanotan II is Ac-Nle-cyclo(Asp-His-D-Phe-Arg-Trp-Lys)-NH2, a seven-residue analog of alpha-MSH residues 4 to 10. A lactam bridge between the aspartate and lysine side chains closes a 23-membered ring, and the peptide is acetylated at one end and amidated at the other.
Which receptors does Melanotan II activate?
Published receptor work describes it as an agonist at MC1R, MC3R, MC4R and MC5R, the four melanocortin receptors that recognize alpha-MSH. MC2R primarily recognizes ACTH peptides. The receptor family signals mainly through intracellular cyclic AMP.
Is Melanotan II approved by the FDA?
No. It has never had an approved application. A 2016 FDA debarment order in the Federal Register describes the agency's 2007 letters stating that Melanotan II as marketed was an unapproved new drug, and FDA's compounding page lists it among withdrawn bulk substance nominations.
$157.50
Melanotan II · 10 mg · 10-vial kit