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Updated: Dec 21, 2025

Quantifying Agonist Activity at G Protein-coupled Receptors
Published on: December 26, 2011
Tetrahydroimidazo[1,2-a]pyrazine Derivatives: Synthesis and Evaluation as Gαq -Protein Ligands
Jim Küppers1, Tobias Benkel2,3, Suvi Annala2
1Pharmaceutical Institute, Department of Pharmaceutical & Medicinal Chemistry, University of Bonn, An der Immenburg 4, 53121, Bonn, Germany.
Abstract:
The 5,6,7,8-tetrahydroimidazo[1,2-a]pyrazine derivative BIM-46174 and its dimeric form BIM-46187 (1) are heterocyclized dipeptides that belong to the very few cell-permeable compounds known to preferentially silence Gαq proteins. To explore the chemical space of Gαq inhibitors of the BIM chemotype, a combinatorial approach was conducted towards a library of BIM molecules. This library was evaluated in a second messenger-based fluorescence assay to analyze the activity of Gαq proteins through the determination of intracellular myo-inositol 1-phosphate. Structure-activity relationships were deduced and structural requirements for biological activity obtained, which were (i) a redox reactive thiol/disulfane substructure, (ii) an N-terminal basic amino group, (iii) a cyclohexylalanine moiety, and (iv) a bicyclic skeleton. Active compounds exhibited cellular toxicity, which was investigated in detail for the prototypical inhibitor 1. This compound affects the structural cytoskeletal dynamics in a Gαq/11 -independent manner.
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