Design, synthesis, and biological evaluation of non-peptidic ligands at the Xenopus laevis skin-melanocortin receptor
摘要:
Taking the tripeptide D-Trp-Arg-Leu-NH2 as a lead for a Xenopus laevis skin-melanocortin (MC) receptor antagonist, thirteen non-peptidic compounds were synthesized and biologically evaluated at Xenopus laevis melanophores. Six competitive antagonists (shown by Schild analysis) and one partial agonist were identified with moderate activity (IC50: 5-10 muM). Tryptophanamides with aliphatic side chains were inactive whereas basic residues restored activity. Introducing an imidazole residue yielded partial agonist activity (EC50: 32 muM). Interestingly, constraining the inactive S-tryptophan-isoamylamide to a beta-carboline ring yielded an MC receptor antagonist (42). The specificity for MC receptors was tested at various G-protein coupled receptors. In conclusion, the synthesis of non-peptidic MC receptor antagonists is described which may serve as lead compounds for further studies. (C) 2003 Editions scientifiques et medicales Elsevier SAS. All rights reserved.
Aerobic, Diselenide-Catalyzed Redox Dehydration: Amides and Peptides
作者:Srirama Murthy Akondi、Pavankumar Gangireddy、Thomas C. Pickel、Lanny S. Liebeskind
DOI:10.1021/acs.orglett.7b03620
日期:2018.2.2
At 2.5 mol % loadings using reaction temperatures between 30–55 °C, ortho-functionalized diaryl diselenides are highly effective organocatalytic oxidants for aerobic redox dehydrative amidic and peptidic bond formation using triethyl phosphite as a simple terminal reductant. This simple-to-perform organocatalytic reaction relies on the ability of selenols to react directly with dioxygen in air without