Melanotan I

Melanotan I (Afamelanotide)

Melanotan I, also known as Afamelanotide, is a synthetic linear tridecapeptide analogue of α-melanocyte-stimulating hormone (α-MSH), developed at the University of Arizona. Unlike Melanotan II, which is a cyclic heptapeptide, Melanotan I retains the full 13-amino acid sequence of α-MSH with a single amino acid substitution ([Nle4, D-Phe7]-α-MSH) that confers enhanced potency and metabolic stability. Melanotan I is a selective MC1R agonist with significantly reduced activity at MC3R and MC4R compared to Melanotan II, making it a more selective research tool for studying MC1R-mediated pigmentation and photoprotection pathways.

Mechanism of Action

Melanotan I acts as a potent, selective agonist of MC1R expressed on epidermal melanocytes. MC1R activation stimulates adenylyl cyclase via Gs-protein coupling, increasing intracellular cAMP and activating the MITF (Microphthalmia-associated Transcription Factor) pathway. This upregulates tyrosinase, TRP-1, and TRP-2 enzyme expression, promoting the synthesis of eumelanin — the photoprotective brown-black pigment — over phaeomelanin. MC1R activation also induces DNA repair mechanisms in melanocytes, including nucleotide excision repair (NER) of UV-induced cyclobutane pyrimidine dimers (CPDs), independent of pigmentation. These dual mechanisms make Melanotan I a valuable tool for studying MC1R pharmacology, melanogenesis, and UV-induced DNA damage repair.

Research Applications

• MC1R pharmacology and selective melanocortin receptor agonism studies
• Melanogenesis, eumelanin synthesis, and MITF pathway research
• UV-induced DNA damage repair and nucleotide excision repair investigation
• Photoprotection and erythropoietic protoporphyria (EPP) preclinical models
• Melanocyte biology and pigmentation disorder research

Specifications

• Molecular Formula: C₇₈H₁₁₁N₂₁O₁₉ ⋅ xC₂H₄O₂
• Molecular Weight:  1706.90 g/mol
• CAS Number: 1566590-77-9
• Purity: ≥98%
• Form: Lyophilised powder
• Storage: -20°C
• Shelf Life: 24 months

This product is intended for legitimate laboratory and analytical research use only. Not for diagnostic, therapeutic, or consumer use.