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Application of the Guanidine–Acylguanidine Bioisosteric Approach to Argininamide‐Type NPY Y 2 Receptor Antagonists
Author(s) -
Pluym Nikola,
Brennauer Albert,
Keller Max,
Ziemek Ralf,
Pop Nathalie,
Bernhardt Günther,
Buschauer Armin
Publication year - 2011
Publication title -
chemmedchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.817
H-Index - 100
eISSN - 1860-7187
pISSN - 1860-7179
DOI - 10.1002/cmdc.201100241
Subject(s) - guanidine , chemistry , neuropeptide y receptor , g protein coupled receptor , stereochemistry , receptor , derivatization , ligand (biochemistry) , amine gas treating , aromatic amine , affinities , biochemistry , neuropeptide , organic chemistry , high performance liquid chromatography
Strongly basic groups such as guanidine moieties are crucial structural elements, but they compromise the drug‐likeness of numerous biologically active compounds, including ligands of G‐protein‐coupled receptors (GPCRs). As part of a project focused on the search for guanidine bioisosteres, argininamide‐type neuropeptide Y (NPY) Y 2 receptor (Y 2 R) antagonists related to BIIE0246 were synthesized. Starting from ornithine derivatives, N G ‐acylated argininamides were obtained by guanidinylation with tailor‐made mono‐Boc‐protected N ‐acyl‐ S ‐methylisothioureas. The compounds were investigated for Y 2 R antagonism (calcium assays), Y 2 R affinity, and NPY receptor subtype selectivity (flow cytometric binding assays). Most of the N G ‐substituted ( S )‐argininamides showed Y 2 R antagonistic activities and binding affinities similar to those of the parent compound, whereas N G ‐acylated or ‐carbamoylated analogues with a terminal amine were superior (Y 2 R: K i and K B values in the low nanomolar range). This demonstrates that the basicity of the compounds, although 4–5 orders of magnitude lower than that of guanidines, is sufficient to form key interactions with acidic amino acids of the Y 2 R. The acylguanidines bind with high affinity and selectivity to Y 2 R over the Y 1 , Y 4 , and Y 5 receptors. As derivatization of the amino group is tolerated, these compounds can be considered building blocks for the preparation of versatile fluorescent and radiolabeled pharmacological tools for in vitro studies of the Y 2 R. The results support the concept of bioisosteric guanidine–acylguanidine exchange as a broadly applicable approach to retain pharmacological activity despite decreased basicity.