Discovery of a Biased Allosteric Modulator for Cannabinoid 1 Receptor: Preclinical Anti-Glaucoma Efficacy

Abstract

We apply the magic methyl effect to improve the potency/efficacy of GAT211, the prototypic 2-phenylindole-based cannabinoid type-1 receptor (CB1R) agonist-positive allosteric modulator (ago-PAM). Introducing a methyl group at the α-position of nitro group generated two diastereomers, the greater potency and efficacy of erythro, (±)-9 vs threo, (±)-10 constitutes the first demonstration of diastereoselective CB1R-allosteric modulator interaction. Of the (±)-9 enantiomers, (−)-(S,R)-13 evidenced improved potency over GAT211 as a CB1R ago-PAM, whereas (+)-(R,S)-14 was a CB1R allosteric agonist biased toward G protein-vs β-arrestin1/2-dependent signaling. (−)-(S,R)-13 and (+)-(R,S)-14 were devoid of undesirable side effects (triad test), and (+)-(R,S)-14 reduced intraocular pressure with an unprecedentedly long duration of action in a murine glaucoma model. (−)-(S,R)-13 docked into both a CB1R extracellular PAM and intracellular allosteric-agonist site(s), whereas (+)-(R,S)-14 preferentially engaged only the latter. Exploiting G-protein biased CB1R-allosteric modulation can offer safer therapeutic candidates for glaucoma and, potentially, other diseases.

Modulation of type 1 cannabinoid receptor activity by cannabinoid by-products from Cannabis sativa and non-cannabis phytomolecules

“…Co-treatment of hCB1R CHO cells with 1 μM PEA and 1 μM SR141716A-or a combination of 1 μM PEA, 1 μM Δ 9 -THC, and 1 μM SR141716A-completely prevented PEA-dependent cAMP inhibition (Figure 5). Previous reports have shown that allosteric or indirect agonism of hCB1R is blocked by SR141716A even when those allosteric ligands are not displaced in radioligand binding experiments (Garai et al, 2020, Garai et al, 2021. Therefore, the collective evidence supports PEA indirectly augmenting the activity of hCB1R in vitro.…”

“…PEA has been described as a partial hCB1R agonist and bears structural similarity to the endogenous cannabinoid anandamide (AEA) (Jonsson et al, 2001;Ho et al, 2008). Therefore, PEA's activity may be consistent with allosteric agonism of hCB1R (Laprairie et al, 2019;Garai et al, 2020Garai et al, , 2021.…”

The Cannabinoid Receptor Type 1 Positive Allosteric Modulator ZCZ011 Attenuates Naloxone-Precipitated Diarrhea and Weight Loss in Oxycodone-Dependent Mice

“…ZCZ011 and related compounds (i.e., GAT211) show mixed allosteric agonistic and PAM properties, which have been termed CB 1 ago-PAMs (Kenakin, 2013). These compounds enhance the effects of CB 1 receptor orthosteric agonists (i.e., CP55,940, WIN55,212-2, or AEA) in a variety of functional assays, including [ 35 S] GTPγS-binding, β-arrestin recruitment and, inhibition of cAMP production, but also activate β-arrestin recruitment and inhibit cAMP production in the absence of CB 1 receptor orthosteric agonists (Ignatowska-Jankowska, Baillie, et al, 2015;Slivicki et al, 2017;Saleh et al, 2018;Tseng et al, 2019;Garai et al, 2021). Thus, additional studies (e.g., site directed mutagenesis) will be required to address the receptor mechanism(s) by which ZCZ011 ameliorates withdrawal signs in opioid-dependent mice.…”

“Magic Chloro”: Profound Effects of the Chlorine Atom in Drug Discovery

“…2 First coined in 2009, 3 the term "magic methyl" has been used frequently since this review was published, both by an increasing number of organic chemists who develop C-H methylation strategies, [4][5][6][7][8][9][10][11] and by medicinal chemists who attribute this term to SAR trends found in their drug discovery programs. [12][13][14][15][16][17][18][19][20][21] As such, the profound effect of this small methyl group in medicinal chemistry has been discussed at length. 2,22,23 Are there other small substituents that could create a similar effect?…”