Ericson MD, Larson CM, Freeman KT, Nicke L, Geyer A, Haskell-Luevano C. Incorporation of Indoylated Phenylalanine Yields a Sub-Micromolar Selective Melanocortin-4 Receptor Antagonist Tetrapeptide.
ACS OMEGA 2022;
7:27656-27663. [PMID:
35967074 PMCID:
PMC9366794 DOI:
10.1021/acsomega.2c03307]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Accepted: 07/06/2022] [Indexed: 06/14/2023]
Abstract
The melanocortin family is involved in many physiological functions, including pigmentation, steroidogenesis, and appetite. The centrally expressed melanocortin-3 and melanocortin-4 receptors (MC3R and MC4R) possess overlapping but distinct roles in energy homeostasis. Herein, the third and fourth positions of a tetrapeptide lead compound [Ac-Arg-Arg-(pI)DPhe-Tic-NH2], previously reported to possess MC3R agonist and MC4R antagonist activities, were substituted with indoylated phenylalanine (Wsf/Wrf) residues in an attempt to generate receptor subtype selective compounds. At the third position, d-amino acids were required for melanocortin agonist activity, while both l- and d-residues resulted in MC4R antagonist activity. These results indicate that l-indoylated phenylalanine residues at the third position of the scaffold can generate MC4R over MC3R selective antagonist ligands, resulting in a substitution pattern that may be exploited for novel MC4R ligands that can be used to probe the in vivo activity of the MC4R without involvement of the MC3R.
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