Design, synthesis and biological evaluation of novel orthosteric-allosteric ligands of the cannabinoid receptor type 2 (CB2R)

Rebecca Ferrisi; Francesca Gado; Beatrice Polini; Caterina Ricardi; Kawthar A Mohamed; Lesley A Stevenson; Gabriella Ortore; Simona Rapposelli; Giuseppe Saccomanni; Roger G Pertwee; Robert B Laprairie; Clementina Manera; Grazia Chiellini

doi:10.3389/fchem.2022.984069

Design, synthesis and biological evaluation of novel orthosteric-allosteric ligands of the cannabinoid receptor type 2 (CB₂R)

Front Chem. 2022 Sep 27:10:984069. doi: 10.3389/fchem.2022.984069. eCollection 2022.

Authors

Rebecca Ferrisi¹, Francesca Gado^{1

2}, Beatrice Polini³, Caterina Ricardi³, Kawthar A Mohamed⁴, Lesley A Stevenson⁵, Gabriella Ortore¹, Simona Rapposelli¹, Giuseppe Saccomanni¹, Roger G Pertwee⁵, Robert B Laprairie^{4

6}, Clementina Manera^{1

7}, Grazia Chiellini^{3

7}

Affiliations

¹ Department of Pharmacy, University of Pisa, Pisa, Italy.
² Department of Pharmaceutical Sciences, University of Milano Statale, Milan, Italy.
³ Department of Pathology, University of Pisa, Pisa, Italy.
⁴ College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, SK, Canada.
⁵ School of Medicine, Medical Sciences and Nutrition, Institute of Medical Sciences, University of Aberdeen, Aberdeen, Scotland, United Kingdom.
⁶ Department of Pharmacology, College of Medicine, Dalhousie University, Halifax, NS, Canada.
⁷ CISUP, Centre for Instrumentation Sharing Pisa University, Pisa, Italy.

Abstract

It is well known that G protein-coupled receptors (GPCRs) assume multiple active states. Orthosteric ligands and/or allosteric modulators can preferentially stabilize specific conformations, giving rise to pathway-biased signaling. One of the most promising strategies to expand the repertoire of signaling-selective GPCR activators consists of dualsteric agents, which are hybrid compounds consisting of orthosteric and allosteric pharmacophoric units. This approach proved to be very promising showing several advantages over monovalent targeting strategies, including an increased affinity or selectivity, a bias in signaling pathway activation, reduced off-target activity and therapeutic resistance. Our study focused on the cannabinoid receptor type 2 (CB₂R), considered a clinically promising target for the control of brain damage in neurodegenerative disorders. Indeed, CB₂R was found highly expressed in microglial cells, astrocytes, and even in some neuron subpopulations. Here, we describe the design, synthesis, and biological evaluation of two new classes of potential dualsteric (bitopic) CB₂R ligands. The new compounds were obtained by connecting, through different linkers, the pharmacophoric portion of the CB₂R positive allosteric modulator (PAM), EC21a, with that of the CB₂R selective orthosteric agonist LV62, both developed in our laboratories. A preliminary screening enabled us to identify compound JR64a as the most promising of the series. Indeed, functional examination highlighted a signaling 'bias' in favor of G protein activation over βarrestin2 recruitment, combined with high affinity for CB₂R and the ability to efficiently prevent inflammation in human microglial cells (HMC3) exposed to LPS/TNFα stimulation, thus demonstrating great promise for the treatment of neurodegenerative diseases.

Keywords: CB2R allosteric modulators; antiinflammatory activity; cannabinoid receptor type 2 (CB2R); dualsteric agents; human microglial cells.