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Melanotan II

Melanocortin
Chemical Profile
Molecular Formula
C50H69N15O9
Molar Mass
1,024.18 g/mol
CAS Number
121062-08-6
Purity Standard
99%+ (HPLC Verified)
Amino Acid Sequence
Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2

Overview

Melanotan II (MT-II) is a synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (alpha-MSH) developed at the University of Arizona for skin cancer prevention research. Its cyclic structure and incorporation of non-natural amino acids provide enhanced metabolic stability compared to linear alpha-MSH.

The compound activates all melanocortin receptor subtypes (MC1R through MC5R), with this non-selective profile producing multiple biological effects. MC1R activation in melanocytes stimulates melanogenesis, producing skin pigmentation that provides some protection against UV-induced DNA damage.

Beyond pigmentation, Melanotan II's activation of central MC3R and MC4R receptors produces effects on sexual function and appetite regulation. The compound was the progenitor of Bremelanotide (PT-141), which was developed with improved MC3R/MC4R selectivity for sexual dysfunction research.

Research has also explored MT-II's potential effects on fat metabolism, inflammation, and cardiovascular function through various melanocortin receptor pathways. However, its non-selective profile means effects are complex and sometimes contradictory, making it valuable for pan-melanocortin studies but less suitable where receptor-specific effects are desired.

Synthesis Overview

Melanotan II is synthesized via Fmoc solid-phase peptide synthesis as a cyclic lactam peptide. The linear precursor is assembled on resin incorporating norleucine (Nle) and D-phenylalanine at designated positions. Following cleavage, the cyclic structure is formed through amide bond formation between the Asp and Lys side chains in dilute solution to minimize oligomerization. The N-terminal is acetylated prior to cyclization. Purification via preparative HPLC separates cyclic monomer from dimers and linear impurities.

Research Applications

  • Non-selective melanocortin receptor (MC1R-MC5R) activation studies
  • Melanogenesis and skin pigmentation mechanism research
  • Photoprotection and DNA damage prevention investigation
  • Sexual function via MC3R/MC4R central pathway studies
  • Appetite regulation and energy homeostasis research
  • Comparative selectivity studies with MC receptor subtype agonists

Related Compounds

Bremelanotide (PT-141)
Melanocortin

C50H68N14O10

1,025.17 g/mol

Bremelanotide (PT-141) is an FDA-approved cyclic melanocortin peptide that represents a paradigm shift in sexual dysfunction therapeutics. Unlike phos...

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Afamelanotide
Melanocortin

C78H111N21O19

1,646.86 g/mol

Afamelanotide is a synthetic tridecapeptide analog of alpha-melanocyte-stimulating hormone (alpha-MSH) designed for enhanced potency and metabolic sta...

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Setmelanotide
Melanocortin

C56H78N16O11S2

1,227.47 g/mol

Setmelanotide is a cyclic peptide MC4R agonist designed with high selectivity for the MC4 receptor over other melanocortin receptor subtypes. This sel...

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