**Background**
The melanocortin system plays a critical role in regulating various physiological processes, including pigmentation, inflammation, and appetite. Central to this system are the melanocortin receptors (MCRs), particularly the melanocortin type 1 receptor (MC1R) located on melanocytes. Activation of MC1R stimulates melanogenesis, leading to the production of melanin and the induction of skin tanning. Beyond pigmentation, the modulation of these receptors is of significant interest in the study of sun-induced skin cancer, melanoma, and inflammatory conditions. Understanding the interaction between synthetic peptides and these receptors provides valuable insights into treating male erectile dysfunction and managing skin pathologies. In this context, we will introduce a potent non-selective melanocortin receptor agonist – Melanotan I.
**Definition**
Melanotan I is a synthetic analogue of $\alpha$-melanocyte stimulating hormone ($\alpha$-MSH) that acts as a potent non-selective melanocortin receptor (MCR) agonist targeting MC1R.
**In Vitro and In Vivo Studies**
According to the Melanotan I description, this peptide mimics the actions of $\alpha$-MSH to stimulate melanogenesis. Regarding Melanotan I in vitro activity, treatment with 1 $\mu$M of the compound for 72 hours has been shown to inhibit melanoma cell proliferation and either slightly inhibit or not alter the formation of tumor colonies.
The Melanotan I In Vivo profile demonstrates a high level of safety and tolerability. In rodent models, administration of 2 mg/kg/day via subcutaneous (s.c.) injection for 12 weeks resulted in no acute toxic effects. Furthermore, in SCID (immunodeficient) mice, doses of 2/10 mg/kg (s.c.) did not increase the incidence of human melanoma tumors, nor did they lead to malignant transformation or exhibit cancer-promoting effects. In rat models, a dosage of 0.6 mg/kg/day for 30 days administered s.c. was well tolerated, showing no changes in lethality or weight gain, and no significant serum chemistry changes, with the exception of a slight increase (30%) in lactic dehydrogenase levels. For researchers requiring specific Melanotan I technical information, the compound is characterized by the formula $\text{C}_{78}\text{H}_{111}\text{N}_{21}\text{O}_{19}$ and a molecular weight of 1646.85. In conclusion, Melanotan I is a potent MC1R agonist that serves as a valuable tool for researching skin pigmentation and Melanotan I Cancer applications.
Keywords
Melanotan I, 75921-69-6, MT-I, [Nle4,D-Phe7]-α-MSH, Melanocortin Receptor, MC Receptor, sub cutaneous injection, human melanocytes, melanotropic peptide, Melanotan, skin cancers, α-MSH, MC1R, melanocortin receptor, Inhibitor, inhibitor, inhibit
References
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[4] Hadley ME, et al. Discovery and development of novel melanogenic drugs. Melanotan-I and -II. Pharm Biotechnol. 1998;11:575-95.