Melanotan II Research Overview: A Non-Selective Melanocortin Agonist
Written from the cited peer-reviewed literature; every product lot is third-party tested.
For research purposes only. This content is intended for educational and informational purposes. Products mentioned are sold strictly for laboratory research use. Not for human consumption. Not for human use. Read more
Melanotan II is a synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (α-MSH), with the structure Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2. It binds several of the melanocortin receptors, which makes it a common non-selective reference compound in receptor pharmacology.
This overview covers the melanocortin receptor system, Melanotan II's structure and origins, and how it relates to other α-MSH analogs.
The melanocortin receptor system
The melanocortins are a family of peptides produced from a precursor protein, pro-opiomelanocortin (POMC). They include α-MSH and ACTH. They act on five receptors, MC1R to MC5R, which differ in where they are found:
- MC1R: melanocytes and some immune cells
- MC2R: the adrenal gland, where it responds to ACTH
- MC3R and MC4R: mainly the central nervous system
- MC5R: exocrine glands and other peripheral tissues
Because the receptors are spread across so many tissues, compounds that activate several of them at once are useful for studying the system as a whole.
Structure and origins
Melanotan II was developed at the University of Arizona in the late 1980s and early 1990s, as part of research into α-MSH analogs that would resist enzymatic breakdown. Its key feature is a lactam bridge that closes part of the peptide into a ring. This cyclic structure makes it far more stable than native α-MSH, which is broken down quickly.
The same research program produced Melanotan I (also known as afamelanotide), a linear analog of α-MSH. Comparing the linear and cyclic versions is a common way to study how ring structures affect stability and receptor binding.
Receptor profile
Melanotan II binds MC1R, MC3R, MC4R and MC5R, but not MC2R, the ACTH receptor. This broad profile is why it is used as a non-selective reference agonist, against which more selective compounds can be compared.
Relationship to PT-141
PT-141 (bremelanotide) is almost identical to Melanotan II. The only difference is at the C-terminus: Melanotan II ends in an amide, while PT-141 ends in a free acid. That small change shifts the receptor profile, and PT-141 is studied mainly for its activity at MC3R and MC4R. The two are often compared in research on how small structural changes affect receptor selectivity. Our PT-141 research overview covers it in more detail.
Laboratory uses
- MC1R signaling in melanocyte cell cultures
- Comparative receptor-binding studies across MC1R, MC3R, MC4R and MC5R
- Structure-activity research on cyclic versus linear α-MSH analogs
Handling in the laboratory
Melanotan II is supplied as a lyophilized powder and is generally reconstituted with bacteriostatic water before use. Sealed vials are stored at -20°C, protected from light and moisture.
Testing and documentation
Every lot we sell is tested by Freedom Diagnostics, an independent laboratory, using HPLC for purity and mass spectrometry for identity. Certificates are published in our COA library, and each can be verified directly with the lab using the search code printed on it. Our guide explains how to verify a COA.
Every lot is third-party tested. View the certificate for Melanotan II →
Related reading
For research purposes only. All products from Canada Research Labs are supplied strictly as reference materials for in-vitro laboratory research by qualified professionals. They are not drugs, natural health products or cosmetics, and have not been authorized by Health Canada for any human or veterinary use.
