Diphenylpyraline Derivatives Are Allosteric Agonists of the CB1 Cannabinoid Receptor
9 affiliations
- 1Jerry M. Wallace School of Osteopathic Medicine, Campbell University, Lillington, NC 27506, USA
- 2Department of Physiology & Pharmacology (Translational Neuroscience), Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
- 3Faculty of Medicine, Al-Azhar University, New Damietta 34518, Egypt
- 4Biomedical Research Infrastructure Center, Winston-Salem State University, Winston-Salem, NC 27101, USA
- 5Department of Biological Sciences, Winston-Salem State University, Winston-Salem, NC 27101, USA
- 6Department of Chemistry, Winston-Salem State University, Winston-Salem, NC 27101, USA
- 7Wake Forest Institute for Regenerative Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
- 8Department of Obstetrics and Gynecology, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
- 9Department of Pharmaceutical & Clinical Sciences, Campbell University, Lillington, NC 27506, USA
Abstract
Diphenylpyraline analogs JKH1 and JKH10 are monoamine transporter inhibitors and promote relaxation in mouse mesenteric arteries. Here, we evaluated JKH1 and JKH for their interaction with CB1 cannabinoid receptor signaling. In N18TG2 mouse neuroblastoma cells that endogenously express CB1 receptors, JKH1 and JKH10 stimulated [35S]GTPγS binding in a concentration-dependent manner; this stimulation was non-competitively antagonized by the CB1 antagonist-inverse agonist SR141716 (1 µM). JKH10 (but not JKH1) inhibited forskolin-stimulated cAMP accumulation with efficacy as high as the full orthosteric agonist WIN55212-2, and this Gi-mediated inhibition was completely precluded by pertussis toxin treatment. However, JKH1 was a poor inhibitor. The SR141716 failed to completely block the inhibition by JKH10. Both JKH analogs stimulated ERK phosphorylation, but inhibition by SR141716 (1 µM) did not appear to be overcome by increasing concentrations of JKH1 or JKH10. In mouse isolated mesenteric arteries, both analogs (1 µM) attenuated the contractile response, but only the response to JKH10 was blocked by the CB1 antagonist-inverse agonist O-2050 (1 µM). Docking studies to protein data bank CB1 structures 7FEE and 6KQI showed JKH1 was predicted to dock predominantly at a pregnenolone-binding site, whereas JKH10 was predicted to dock at both the pregnenolone and a cholesterol consensus motif at helices 2–3–4 inner membrane leaflet. Thus, a series of diphenylpyraline derivatives can behave as CB1 receptor stimulators, and in silico evidence supports that this could result from interaction with cholesterol and/or pregnenolone protein surface binding sites rather than the orthosteric binding site.
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BibTeX
@article{eldeeb2026diphenylpyraline,
title = {{Diphenylpyraline Derivatives Are Allosteric Agonists of the CB1 Cannabinoid Receptor}},
author = {Khalil Eldeeb and Jill K. Harp and Ryan W. Fitzgerald and Sandra Leone-Kabler and Tony E. Reeves and Sara R. Jones and Steve R. Childers and Allyn C. Howlett and Victor M. Pulgar},
journal = {Molecules},
year = {2026},
month = oct,
doi = {10.3390/molecules31203699},
url = {https://www.mdpi.com/1420-3049/31/20/3699},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Diphenylpyraline Derivatives Are Allosteric Agonists of the CB1 Cannabinoid Receptor
AU - Khalil Eldeeb
AU - Jill K. Harp
AU - Ryan W. Fitzgerald
AU - Sandra Leone-Kabler
AU - Tony E. Reeves
AU - Sara R. Jones
AU - Steve R. Childers
AU - Allyn C. Howlett
AU - Victor M. Pulgar
PY - 2026
DA - 2026/10/01
JO - Molecules
DO - 10.3390/molecules31203699
UR - https://www.mdpi.com/1420-3049/31/20/3699
AB - Diphenylpyraline analogs JKH1 and JKH10 are monoamine transporter inhibitors and promote relaxation in mouse mesenteric arteries. Here, we evaluated JKH1 and JKH for their interaction with CB1 cannabinoid receptor signaling. In N18TG2 mouse neuroblastoma cells that endogenously express CB1 receptors, JKH1 and JKH10 stimulated [35S]GTPγS binding in a concentration-dependent manner; this stimulation was non-competitively antagonized by the CB1 antagonist-inverse agonist SR141716 (1 µM). JKH10 (but not JKH1) inhibited forskolin-stimulated cAMP accumulation with efficacy as high as the full orthosteric agonist WIN55212-2, and this Gi-mediated inhibition was completely precluded by pertussis toxin treatment. However, JKH1 was a poor inhibitor. The SR141716 failed to completely block the inhibition by JKH10. Both JKH analogs stimulated ERK phosphorylation, but inhibition by SR141716 (1 µM) did not appear to be overcome by increasing concentrations of JKH1 or JKH10. In mouse isolated mesenteric arteries, both analogs (1 µM) attenuated the contractile response, but only the response to JKH10 was blocked by the CB1 antagonist-inverse agonist O-2050 (1 µM). Docking studies to protein data bank CB1 structures 7FEE and 6KQI showed JKH1 was predicted to dock predominantly at a pregnenolone-binding site, whereas JKH10 was predicted to dock at both the pregnenolone and a cholesterol consensus motif at helices 2–3–4 inner membrane leaflet. Thus, a series of diphenylpyraline derivatives can behave as CB1 receptor stimulators, and in silico evidence supports that this could result from interaction with cholesterol and/or pregnenolone protein surface binding sites rather than the orthosteric binding site.
SN - 1420-3049
ER -