Overview
Melanotan II is a synthetic cyclic heptapeptide analog of alpha-melanocyte stimulating hormone (α-MSH), structurally engineered with a cyclic lactam bridge for enhanced metabolic stability and receptor affinity. The compound has been studied in preclinical research as a non-selective melanocortin receptor agonist, with particular research interest in MC1R and MC4R pathway pharmacology (Hruby et al., 1987 — PMID: 3031204).
History
Melanotan II was developed at the University of Arizona in the 1980s through structure-activity optimization research on α-MSH. Early research focused on investigating melanocortin receptor pharmacology and the molecular determinants of receptor selectivity across the MC1-MC5 receptor subtypes. Research has since expanded to include melanocortin pathway studies in metabolic and reproductive models (Dorr et al., 1996).
Structure & Molecular Data
| CAS Number | 121062-08-6 |
| Molecular Formula | C₅₀H₆₉N₁₅O₉ |
| Molecular Weight | 1,024.18 g/mol |
| Amino Acid Count / Structure | 7-amino-acid cyclic lactam heptapeptide |
| PubChem CID | 16137315 |
| Sequence | Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂ |
| Appearance | Lyophilized white powder |
| Storage | Store at -20°C. Protect from light and moisture. |
| Solubility | Soluble in sterile water and bacteriostatic water |
Compound Class & Mechanism
Melanotan II acts as a non-selective agonist at melanocortin receptors (MC1R, MC3R, MC4R, and MC5R), with research documenting affinity across all four receptor subtypes. Melanocortin receptor activation signals primarily through Gs protein-coupled pathways, triggering cAMP accumulation and downstream transcriptional responses in preclinical models.
The compound’s cyclic lactam structure confers enhanced proteolytic resistance and receptor affinity relative to native α-MSH. Research has characterized MT-II activity across multiple pathway contexts including MC1R-mediated melanocyte signaling, MC4R-mediated pathway research in hypothalamic energy homeostasis models, and MC3R/MC4R research in sexual behavior preclinical models (Wessells et al., 2000).
Research Findings
Melanotan II has been investigated in preclinical research spanning melanocortin receptor pharmacology, pigmentation research, metabolic pathway studies, and reproductive behavior research. Published research has documented findings in the following domains:
Key Research Areas
- Melanocortin Receptor Pharmacology: MC1-MC5 receptor binding profile studies
- Pigmentation Research: MC1R-mediated melanogenesis research in preclinical models
- Metabolic Pathway Research: MC4R hypothalamic energy homeostasis research
- Reproductive Behavior Research: MC3R/MC4R reproductive pathway research in animal models
Collectively, Melanotan II has been established as a foundational research tool for investigating non-selective melanocortin receptor pharmacology and pathway biology across multiple receptor subtypes (Hadley & Dorr, 2006).
Research Context
Researchers study Melanotan II to investigate melanocortin receptor pharmacology, particularly in contexts requiring pan-MC receptor engagement. Its non-selective profile distinguishes it from more selective melanocortin-targeted research compounds.
References
Hruby VJ. et al. (1987). Cyclic lactam alpha-melanotropin analogues of Ac-Nle4-c[Asp5, D-Phe7, Lys10]-alpha-MSH(4-10)-NH2 with bulky aromatic amino acids at position 7 show high antagonist potency and selectivity at specific melanocortin receptors. Journal of Medicinal Chemistry. PMID: 3031204
Dorr RT. et al. (1996). Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide. Annals of the New York Academy of Sciences.
Wessells H. et al. (2000). Melanocortin receptor agonists and male sexual behavior. Peptides.
Hadley ME., Dorr RT. (2006). Melanocortin peptide therapeutics: historical milestones and current status. Peptides.
Ugwu SO. et al. (1997). Skin pigmentation and pharmacokinetics of melanotan-I in humans. Biopharmaceutics & Drug Disposition.
Sawyer TK. et al. (1980). 4-Norleucine, 7-D-phenylalanine-alpha-melanocyte-stimulating hormone: a highly potent alpha-melanotropin with ultralong biological activity. PNAS.
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