Melanotan I & II Peptides (MT-I/MT-II) for Research
Melanotan I & II – Synthetic α‑MSH Analog Peptides for Melanocortin Research
Basic Information
| Parameter | Melanotan I | Melanotan II |
|---|---|---|
| CAS Number | 75921‑69‑6 | 121062‑08‑6 |
| Molecular Formula | C₇₈H₁₁₁N₂₁O₁₉ | C₅₀H₆₉N₁₅O₉ |
| Molecular Weight | 1646.85 g/mol | 1024.18 g/mol |
| Appearance | White to off‑white solid powder | White powder |
| Purity | ≥98% (HPLC) | ≥98% (HPLC) |
| Sequence | Ac‑Ser‑Tyr‑Ser‑{Nle}‑Glu‑His‑{d‑Phe}‑Arg‑Trp‑Gly‑Lys‑Pro‑Val‑NH₂ | Ac‑{Nle}‑Asp‑His‑{d‑Phe}‑Arg‑Trp‑Lys‑NH₂ (cyclic) |
Overview
Melanotan I (MT‑I, afamelanotide) and Melanotan II (MT‑II) are synthetic analogs of α‑melanocyte‑stimulating hormone (α‑MSH) developed at the University of Arizona in the 1980s. Both compounds are melanocortin receptor agonists that stimulate melanogenesis (melanin production) in melanocytes, resulting in increased skin pigmentation.
Key Differences
| Feature | Melanotan I | Melanotan II |
|---|---|---|
| Structure | Linear 13‑amino acid peptide | Cyclic peptide (lactam bridge) |
| Receptor Selectivity | Selective for MC1R (tanning receptor) | Non‑selective: MC1R, MC3R, MC4R, MC5R |
| Duration | Shorter action | Longer action |
| Primary Effect | Skin tanning & photoprotection | Tanning + appetite suppression + sexual function effects |
| Regulatory Status | FDA/EMA‑approved for erythropoietic protoporphyria (Scenesse) | No approved indication worldwide |
Applications
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Pigmentation research: Both peptides induce eumelanin production, providing a natural, UV‑independent tan.
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Photoprotection studies: Melanotan I is being studied for photodermatoses, polymorphic light eruption, and non‑melanoma skin cancer prevention.
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Melanocortin receptor research: MT‑II is used to study MC1R, MC3R, MC4R, and MC5R signaling involved in pigmentation, energy homeostasis, sexual function, and immune regulation.
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Appetite and metabolic studies: MT‑II inhibits food intake in experimental models via MC4R activation.
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Erectile function research: MT‑II has been studied for erectile dysfunction (nasal PT‑141 formulation).
Handling and Storage
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Store lyophilized powder at –20°C (up to 1 year) or –80°C (up to 2 years).
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Avoid moisture and repeated freeze‑thaw cycles.
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Unstable in solution — freshly prepare and use immediately.
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For research use only; not for human therapeutic or diagnostic use.
