[Nle4,D-Phe7]-α-MSH (acetate)

[Nle⁴,D-Phe⁷]-α-Melanocyte-stimulating hormone ([Nle⁴,D-Phe⁷]-α-MSH) is a peptide agonist of melanocortin receptor 1 (MC1R).¹ It induces cAMP accumulation in mouse L-cells expressing human MC1R (EC₅₀ = 0.5 nM). It also induces tyrosinase activity in mouse melanoma cells.² In vivo, [Nle⁴,D-Phe⁷]-α-MSH (1.8 mg/kg) induces long-term skin darkening in frogs (R. pipiens).³ Formulations containing [Nle⁴,D-Phe⁷]-α-MSH have been used in the treatment of erythropoietic protoporphyria and as tanning agents.

References:
[1]. Haskell-Luevano, C., Miwa, H., Dickinson, C., et al.Binding and cAMP studies of melanotropin peptides with the cloned human peripheral melanocortin receptor, hMC1RBiochem. Biophys. Res. Commun.204(30)1137-1147(1994).
[2]. Sawyer, T.K., Sanfilippo, P.J., Hruby, V.J., et al.4-Norleucine, 7-D-phenylalanine-α-melanocyte-stimulating hormone: A highly potent α-melanotropin with ultralong biological activityProc. Natl. Acad. Sci. USA77(10)5754-5758(1980).
[3]. Hadley, M.E., Anderson, B., Heward, C.B., et al.Calcium-dependent prolonged effects on melanophores of [4-norleucine, 7-D-phenylalanine]-α-melanotropin.Science213(4511)1025-1027(1981).