Piperazine squaric acid diamides, a novel class of allosteric P2X7 receptor antagonists

• Published in: European journal of medicinal chemistry 2021-12, Vol.226, p.113838-113838, Article 113838
• Main Authors: Patberg, Marius, Isaak, Andreas, Füsser, Friederike, Ortiz Zacarías, Natalia V., Vinnenberg, Laura, Schulte, Janine, Michetti, Lucia, Grey, Lucie, van der Horst, Cas, Hundehege, Petra, Koch, Oliver, Heitman, Laura H., Budde, Thomas, Junker, Anna
• Format: Article
• Language: English
• Subjects: Allosteric; Antagonists; Cyclobutanes - chemical synthesis; Cyclobutanes - chemistry; Cyclobutanes - pharmacology; Diamide - chemical synthesis; Diamide - chemistry; Diamide - pharmacology; Dose-Response Relationship, Drug; HEK293 Cells; Humans; Molecular Structure; P2X; P2X7 receptor; Piperazine - chemical synthesis; Piperazine - chemistry; Piperazine - pharmacology; Purinergic P2X Receptor Antagonists - chemical synthesis; Purinergic P2X Receptor Antagonists - chemistry; Purinergic P2X Receptor Antagonists - pharmacology; Receptors, Purinergic P2X - metabolism; Squaric acid; Structure-Activity Relationship; Tumor Cells, Cultured
• ISSN: 0223-5234; 1768-3254
• DOI: 10.1016/j.ejmech.2021.113838

The P2X7 receptor (P2X7R) stands out among the purinergic receptors due to its strong involvement in the regulation of tumor growth and metastasis formation as well as in innate immune responses and afferent signal transmission. Numerous studies have pointed out the beneficial effects of P2X7R antagonism for the treatment of a variety of cancer types, inflammatory diseases, and chronic pain. Herein we describe the development of novel P2X7R antagonists, incorporating piperazine squaric diamides as a central element. Besides improving the antagonists’ potency from pIC50 values of 5.7–7.6, ADME properties (logD7.4 value, plasma protein binding, in vitro metabolic stability) of the generated compounds were investigated and optimized to provide novel P2X7R antagonists with drug-like properties. Furthermore, docking studies revealed the antagonists binding to the allosteric binding pocket in two distinct binding poses, depending on the substitution of the central piperazine moiety. Herein we describe the development of novel P2X7R antagonists, incorporating piperazine squaric diamides as a central element. The antagonists’ potency was improved from pIC50-values of 5.7–7.6 (YO-PRO assay), the most potent derivatives were further characterized electrophysiologically in whole-cell patch-clamp experiments, and their ADME properties (logD7.4-value, plasma protein binding, in vitro metabolic stability) were investigated and optimized to provide novel P2X7R antagonists with drug-like properties. [Display omitted] •Piperazine squaric acid diamides as a novel class of allosteric P2X7 receptor antagonists.•Squaric acid amide as bioisosteric replacement of cyanoguanidine moiety.•The introduction of a phenyl group at the piperazine ring changes the allosteric binding mode.