Melanotan II developed at the University of Arizona is a synthetic analog of the naturally occurring melanocortin peptide hormone alpha-melanocyte stimulating hormone (α-MSH) that in usage has been shown to have melanogenesis (tanning) and aphrodisiac effects in preliminary studies and clinical trials. It is a cyclic lactam analog of α-MSH with the amino acid sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2.