Structure-activity relationship of linear peptide Bu-His6-DPhe7-Arg8-Trp9-Gly10-NH2 at the human melanocortin-1 and -4 receptors: DPhe7 and Trp9 substitution.

Abstract A series of pentapeptides, based on hMC4R pentapeptide agonist (Bu-His 6 -DPhe 7 -Arg 8 -Trp 9 -Gly 10 -NH 2 ), was prepared in which either DPhe 7 or Trp 9 residue was systematically substituted. A number of interesting DPhe surrogates (D-Thi, D-3-CF 3 Phe, D-2-Nal and D-3,4-diClPhe) as well as Trp surrogates (2-Nal and Bta) were identified in this study.