Melanotan 1 (MT-1) is a synthetic peptide and analogue of alpha-melanotocyte stimulating hormone, an agonist of melanocortin receptors 1, 3, 4, and 5. MT-1 was first developed as a sunless tanning agent, as its ability to bind to melanocortin receptor 1 causes skin to produce more melanin, turning it darker.
It is now approved as afamelanotide in both the United States and Europe to prevent sun-related skin damage in patients with erythropoietic protoporphyria. Most commonly used as a skin tanning agent, the peptide is also being investigated for its potential to treat conditions like vitiligo, rosacea, and erectile dysfunction.