α-MSH Analogues & Fragments

How these compounds are grouped

α-MSH is residues 138–150 of human pro-opiomelanocortin (POMC), Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val, acetylated at the N-terminus and amidated at the C-terminus ^{[1, 3]}.

The melanocortin receptors, MC1R to MC5R, are G protein-coupled receptors for the peptide products of POMC. MC1R and MC4R, for example, both bind α-MSH ^{[2, 5, 8]}.

Cyclic analogues: MT-2 and PT-141

In 1989 a University of Arizona group reported a class of cyclic analogues of α-MSH fragments, closed by a lactam bridge between the side chains of an aspartic or glutamic acid and a lysine or related residue ^[3]. One of them, Ac-[Nle4, Asp5, D-Phe7, Lys10]-α-MSH(4–10)-NH2, is the structure later studied as Melanotan II (MT-II) ^{[3, 9]}.

PT-141, bremelanotide, has the same ring and differs at the C-terminus, a free acid in place of the amide. It was developed as an analogue of MT-II ^{[4, 5]}.

The FDA label for bremelanotide describes it as a melanocortin receptor agonist that activates several receptor subtypes non-selectively, most potently MC1R and then MC4R ^[5].

A fragment: KPV

KPV is the tripeptide Lys-Pro-Val, the last three residues (11–13) of α-MSH ^[1]. It is a piece of the natural sequence rather than a designed analogue, and it lies outside residues 4–10, the part of α-MSH on which the cyclic analogues are based ^{[1, 3]}.

Regulatory status

Bremelanotide is the active ingredient of a prescription drug approved by the FDA (Drugs@FDA application 210557) ^[6]. The material supplied here is a research chemical, not that drug product.

Melanotan II and KPV are not listed as approved drugs in the FDA's Drugs@FDA database (searched 24 September 2026) ^[7].

Every product on this page is supplied for laboratory research use only. None is for human or veterinary use.

Related products

One catalog blend contains a member of this group and is listed for reference rather than as a member.

• KLOW: A four-peptide blend that contains 10 mg of KPV per vial, as printed on its batch report.

Identity data and batch reports

Each product page lists the compound's registry identity data with its source, and every published Certificate of Analysis for the batch supplied. Products without a published report say so.

• Reading peptide identity data: CAS, formula and sequence notation
• How to read a Certificate of Analysis
• Browse the COA Library

References

1. UniProt Consortium UniProtKB P01189: Pro-opiomelanocortin (POMC); chain Melanocyte-stimulating hormone alpha, residues 138–150. UniProt. 2026. Source
2. UniProt Consortium UniProtKB Q01726: Melanocyte-stimulating hormone receptor (MC1R), function. UniProt. 2026. Source
3. Al-Obeidi F, Castrucci AM, Hadley ME, Hruby VJ. Potent and prolonged acting cyclic lactam analogues of alpha-melanotropin: design based on molecular dynamics. Journal of Medicinal Chemistry. 1989;32(12):2555–2561. doi:10.1021/jm00132a010 PubMed 2555512
4. Hadley ME, Dorr RT. Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialization. Peptides. 2006;27(4):921–930. doi:10.1016/j.peptides.2005.01.029 PubMed 16412534
5. U.S. Food and Drug Administration Bremelanotide prescribing information, sections 11 (Description) and 12.1 (Mechanism of Action), via openFDA drug label. open.fda.gov. 2026. Source
6. U.S. Food and Drug Administration Drugs@FDA application 210557: Bremelanotide. accessdata.fda.gov. 2026. Source
7. U.S. Food and Drug Administration Drugs@FDA: FDA-Approved Drugs (searched by active ingredient, 24 September 2026). accessdata.fda.gov. 2026. Source
8. UniProt Consortium UniProtKB P32245: Melanocortin receptor 4 (MC4R), function. UniProt. 2026. Source
9. Dorr RT, Lines R, Levine N, et al. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sciences. 1996;58(20):1777–1784. doi:10.1016/0024-3205(96)00160-9 PubMed 8637402