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Research Catalog

Compound monograph

alpha-MSH

alpha-MSH is the endogenous thirteen-residue melanocortin peptide hormone from which several of the synthetic compounds in this library are derived.

Published: 2026-09-13Last updated: 2026-10-15Literature/identifier verification: 2026-09-13
Also known asα-MSHalpha-MSHalpha-melanotropinMelanotropin alpha
Melanocortin receptor ligands

01

Identity & nomenclature

alpha-MSH is the endogenous thirteen-residue melanocortin peptide hormone from which several of the synthetic compounds in this library are derived.

This is the native hormone, not an analog. It is not afamelanotide: the parent retains Met4 and L-Phe7, and the analog's norleucine and D-phenylalanine substitutions must not migrate into the parent's identity fields. Nor is it simply 'ACTH(1-13)' — the N-acetyl and C-amide processing distinguish it from an uncapped fragment. KPV is its C-terminal tripeptide sequence and nothing more; see structuralNotes.

Canonical name: alpha-Melanocyte-stimulating hormone.

Declared aliases and development codes: α-MSH, alpha-MSH, alpha-melanotropin, Melanotropin alpha.

02

Molecular properties

Molecular formulaC77H109N21O19S
Molecular mass1664.91 Da
CAS Registry Number581-05-5
PubChem CID16133793
UNIIOVF025LA77
One-letter sequenceSYSMEHFRWGKPV
Three-letter sequenceSer–Tyr–Ser–Met–Glu–His–Phe–Arg–Trp–Gly–Lys–Pro–Val
Terminal groupsN-terminal acetylation; C-terminal amide

Thirteen residues, all L, linear, N-terminally acetylated and C-terminally amidated. The 'Ac' is the acetyl cap, not amino-acid letters.

03

Structural characteristics

An agonist at MC1R, MC3R, MC4R and MC5R, with receptor-bound structures establishing MC1R and MC4R recognition; it is not the canonical agonist at MC2R, which responds to ACTH. One caution matters for this library specifically: a fragment of alpha-MSH does not inherit its receptor profile. Comparative work reports that the C-terminal tripeptide KPV retains an anti-inflammatory effect that was NOT blocked by the MC3/4R antagonist SHU9119 and did not raise cAMP, and concludes it likely acts through a mechanism other than the melanocortin receptors. Sequence ancestry is a structural relationship, not a pharmacological one.

Terminal features: N-terminal acetylation, C-terminal amide.

04

Molecular targets & mechanisms

Melanocortin receptors

MC1R · MC2R · MC3R · MC4R · MC5R · MCR

A family of five G protein-coupled receptors, MC1R through MC5R. ACTH recognition and signaling at MC2R depend on the accessory protein MRAP. Native hormones, peptide analogs and nonpeptide ligands differ in receptor-subtype recognition and functional direction; binding affinity, agonism and antagonism must be interpreted separately in the experimental system studied.

05

Analytical considerations

Confirmation requires the thirteen-residue sequence, Met4, the N-acetyl cap and the C-terminal amide, plus a methionine-oxidation assessment. The parent must be distinguished from the Nle4/D-Phe7 analog: those differ compositionally and are separable by mass, but mass alone establishes no D/L configuration. Detecting KPV after hydrolysis or degradation does not show the intact parent was present.

Disagreements and mix-ups

Points where sources disagree about this compound's identity, or where a name or form is easily confused with another, as noted in this record. The discrepancy register quotes the passage for each one.

What the studies reported

Each finding describes one cited study in its stated model. These observations are specific to that study and do not establish effects in other settings.

Cell and tissue studies

  • Macrophage KC and interleukin-1β release assay

    Using a macrophage KC and interleukin-1β release assay, the study observed inhibited macrophage activation with alpha-MSH.

    Reference [1]

  • α-MSH-bound MC1R-Gs cryo-electron microscopy preparation

    Using an α-MSH-bound MC1R-Gs cryo-electron microscopy preparation, the study identified an orthosteric pocket for the conserved HFRW motif.

    Reference [3]

  • α-MSH-bound MC1R-Gs structural preparation

    Using an α-MSH-bound MC1R-Gs structural preparation, the study identified a crucial role for calcium ion in ligand binding.

    Reference [3]

  • Full-length MC4R-heterotrimeric Gs cryo-electron microscopy preparation

    Using a full-length MC4R-heterotrimeric Gs cryo-electron microscopy preparation, the study reported a receptor complex stimulated by α-MSH.

    Reference [4]

Animal studies

  • Mice with crystal-induced peritonitis

    In mice with crystal-induced peritonitis, the study observed a significant reduction in peritoneal polymorphonuclear leukocyte accumulation with alpha-MSH.

    Reference [1]

06

Verified bibliography

Cited studies by type

The 4 papers this record cites, counted by the kind of work each reports. A count is the size of this record's selection, not of the research that exists, and says nothing about results, safety, effectiveness or approval.

A paper can report more than one kind of work. Each count opens those papers in the bibliography. Compare every record on the Evidence Map.

  1. Reference 1

    Dissection of the anti-inflammatory effect of the core and C-terminal (KPV) alpha-melanocyte-stimulating hormone peptides.

    Getting SJ, Schiöth HB, Perretti M

    The Journal of pharmacology and experimental therapeutics · 2003-05-15 · Journal Article

    current
    PMID 12750433DOI 10.1124/jpet.103.051623alpha-MSHSHU9119KPVMelanotan IIMC1R

  2. Reference 2

    Use of chimeric melanocortin-2 and -4 receptors to identify regions responsible for ligand specificity and dependence on melanocortin 2 receptor accessory protein.

    Hinkle PM, Serasinghe MN, Jakabowski A, Sebag JA, Wilson KR, Haskell-Luevano C

    European journal of pharmacology · 2011-01-03 · Journal Article

    current
    PMID 21211532PMC3095721DOI 10.1016/j.ejphar.2010.10.113alpha-MSHCosyntropin (ACTH 1-24)MC1R

  3. Reference 3

    Structural mechanism of calcium-mediated hormone recognition and Gβ interaction by the human melanocortin-1 receptor.

    Ma S, Chen Y, Dai A, Yin W, Guo J, Yang D, Zhou F, Jiang Y, Wang MW, Xu HE

    Cell research · 2021-08-27 · Journal Article

    current
    PMID 34453129PMC8486761DOI 10.1038/s41422-021-00557-yMelanotan I (Afamelanotide)alpha-MSHSHU9119MC1R

  4. Reference 4

    Structural insights into ligand recognition and activation of the melanocortin-4 receptor.

    Zhang H, Chen LN, Yang D, Mao C, Shen Q, Feng W, Shen DD, Dai A, Xie S, Zhou Y, Qin J, Sun JP, Scharf DH, Hou T, Zhou T, Wang MW, Zhang Y

    Cell research · 2021-08-25 · Journal Article

    current
    PMID 34433901PMC8563965DOI 10.1038/s41422-021-00552-3PT-141 (Bremelanotide)Melanotan I (Afamelanotide)alpha-MSHTHIQSetmelanotideMC1R

Study models of these references

What kind of experiment each cited paper reports, taken from its abstract unless marked. Not a summary of results.

ReferenceStudy models
Getting SJ et al. 2003Study models reported: in vitro; animal (mouse) · from the abstract
Hinkle PM et al. 2011Study models reported: in vitro · from the abstract
Ma S et al. 2021Study models reported: in vitro · from the abstract
Zhang H et al. 2021Study models reported: in vitro · from the abstract

Record history

Published 2026-09-13.

  • : Sequence and structure

Each entry names the parts of this record that changed on that date. Changes to links between records and to catalogue links are not listed. This history covers the tracked record fields; study findings are not listed here.

Cite this record: Purely Peptides Research Library. alpha-MSH. Published 2026-09-13; updated 2026-10-15. https://purelypeptides.org/research/compounds/alpha-msh/

10

Methodology & citation verification

Reference identity is checked against official PubMed metadata. Local deterministic receipts bind each normalized title and canonical metadata record to its verification date. Scientific values remain absent when an authoritative source has not been verified.

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