Melanotan-1 ([Nle4-D-Phe7]-α-MSH) is a 13 amino acid linear peptide in which the fourth amino acid, methionine, is replaced with norleucine and the seventh amino acid, L-phenylalanine, is replaced with D-phenylalanine. This molecule is more resistant to breakdown than its natural analogue, which means that the stimulus received by its receptor (principally MC1R) is more potent.
