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Research Catalog

Compound monograph

SHU9119

SHU9119 is a cyclic lactam melanocortin analog whose receptor behaviour is subtype-dependent: antagonist at some melanocortin receptors and agonist at others.

Published: 2026-09-13Literature/identifier verification: 2026-09-13
SHU-9119SHU 9119Cyclic melanocortin analogsMelanocortin receptor ligands

01

Identity & nomenclature

SHU9119 is a cyclic lactam melanocortin analog whose receptor behaviour is subtype-dependent: antagonist at some melanocortin receptors and agonist at others.

SHU9119 shares the Melanotan II ring architecture and differs by a single substitution, D-Phe to D-2-Nal, a net C4H2 or 50.0157 Da. Shared ring architecture does not mean shared pharmacological direction — see structuralNotes. Calling it 'the melanocortin blocker' conceals the central experimental limitation of the compound.

Declared aliases and development codes: SHU-9119, SHU 9119.

02

Molecular properties

Molecular formulaC54H71N15O9
Molecular mass1074.26 Da
CAS Registry Number168482-23-3
PubChem CID6440621
Three-letter sequenceAc–Nle–Asp–His–D-2-Nal–Arg–Trp–Lys–NH2

Seven residues closed by a LACTAM between the Asp2 side-chain carboxyl and the Lys7 epsilon-amino group. D-2-Nal is 3-(naphthalen-2-yl)-D-alanine, one residue. No disulfide, no head-to-tail closure, and no safe linear string.

03

Structural characteristics

The original structure-activity work reports it as a potent MC4R antagonist and a less potent MC3R antagonist, both with minimal agonist activity, while behaving as a FULL AGONIST at MC1 and MC5 receptors. It is therefore not a pan-melanocortin antagonist, and its antagonism must not be transferred from MC4R to every experiment involving a melanocortin receptor. Receptor-bound structures exist at both MC4R — where calcium was identified as a ligand-binding cofactor — and MC1R, giving an unusually direct structural account of why one scaffold can act in opposite directions at two subtypes.

  • Asp2-Lys7 side-chain lactam
  • D-2-naphthylalanine at position 4

Terminal features: N-terminal acetylation at Nle1, C-terminal amide at Lys7.

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

Establishing the Asp2-Lys7 lactam requires NMR or a validated orthogonal method; disulfide reduction is not a ring-opening strategy for a lactam and will not report on it. Verify D-2-Nal stereochemistry and the naphthyl attachment position. The expected mass separates SHU9119 from Melanotan II but not from every stereochemical or positional isomer, and an MC4R antagonist response is supportive functional evidence rather than chemical identification.

06

Verified bibliography

  1. Cyclic lactam alpha-melanotropin analogues of Ac-Nle4-cyclo[Asp5, D-Phe7,Lys10] alpha-melanocyte-stimulating hormone-(4-10)-NH2 with bulky aromatic amino acids at position 7 show high antagonist potency and selectivity at specific melanocortin receptors.

    Hruby VJ, Lu D, Sharma SD, Castrucci AL, Kesterson RA, al-Obeidi FA, Hadley ME, Cone RD

    Journal of medicinal chemistry · 1995-09-01 · Journal Article

    current
    PMID 7658432DOI 10.1021/jm00018a005SHU9119MC1R
  2. Determination of the melanocortin-4 receptor structure identifies Ca(2+) as a cofactor for ligand binding.

    Yu J, Gimenez LE, Hernandez CC, Wu Y, Wein AH, Han GW, McClary K, Mittal SR, Burdsall K, Stauch B, Wu L, Stevens SN, Peisley A, Williams SY, Chen V, Millhauser GL, Zhao S, Cone RD, Stevens RC

    Science (New York, N.Y.) · 2020-04-24 · Journal Article

    current
    PMID 32327598PMC7567314DOI 10.1126/science.aaz8995SHU9119MC1R
  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. 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

10

Methodology & citation verification

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