Design, synthesis, and structure–activity relationships of diindolylmethane derivatives as cannabinoid CB₂ receptor agonists

Abstract

3,3′-Diindolylmethane (DIM), a natural product-derived compound formed upon ingestion of cruciferous vegetables, was recently described to act as a partial agonist of the anti-inflammatory cannabinoid (CB) receptor subtype CB 2 . In the present study, we synthesized and evaluated a series of DIM derivatives and determined their affinities for human CB receptor subtypes in radioligand binding studies. Potent compounds were additionally evaluated in functional cAMP accumulation and β-arrestin recruitment assays. Small substituents in the 4-position of both indole rings of DIM were beneficial for high CB 2 receptor affinity and efficacy. Di-(4-cyano-1H-indol-3-yl)methane (46, PSB-19837, EC 50 : cAMP, 0.0144 µM, 95% efficacy compared to the full standard agonist CP55,940; β-arrestin, 0.0149 µM, 67% efficacy) was the most potent CB 2 receptor agonist of the present series. Di-(4-bromo-1H-indol-3-yl)methane (44, PSB-19571) showed higher potency in β-arrestin (EC 50 0.0450 µM, 61% efficacy) than in cAMP accumulation assays (EC 50 0.509 µM, 85% efficacy) while 3-((1H-indol-3-yl)methyl)−4methyl-1H-indole (149, PSB-18691) displayed a 19-fold bias for the G protein pathway (EC 50 : cAMP, 0.0652 µM; β-arrestin, 1.08 µM). DIM and its analogs act as allosteric CB 2 receptor agonists. These potent CB 2 receptor agonists have potential as novel drugs for the treatment of inflammatory diseases.

Minor, Nonterpenoid Volatile Compounds Drive the Aroma Differences of Exotic Cannabis

“…50 For instance, the compound 3− 3′-diindolylmethane (DIM), which can be considered two skatole molecules fused together through the 3-positioned methyl group, has shown promising anticancer effects, as well as been found to be a CB2 receptor agonist. 51,52 Future investigations into the possible biological activity of these compounds and others reported here may further shed light on how they may influence the properties of specific varieties.…”

Potent, Selective Agonists for the Cannabinoid-like Orphan G Protein-Coupled Receptor GPR18: A Promising Drug Target for Cancer and Immunity

“…Recruitment of β-arrestin-2 to the respective receptor was detected by using the β-galactosidase enzyme fragment complementation technology (β-arrestin PathHunter assay, DiscoverX, Fremont, CA, USA) according to previously published procedures. ,,, In brief, CHO cells stably expressing the respective receptor were seeded in a volume of 90 μL into a 96-well plate at a density of 25,000–30,000 cells/well in a suitable growth medium (cell plating reagent 2, DiscoverX, or OptiMEM, Thermo Fisher) supplemented with 2% fetal calf serum, 100 U/mL penicillin, 100 μg/mL streptomycin, 800 μg/mL geneticin and 300 μg/mL hygromycin, and incubated for 24 h at 37 °C. All test compounds were dissolved in DMSO (except for resolvin D2 (RvD2) which was dissolved either in DMSO or in ethanol, respectively).…”

“…2-(8-((2-(1H-Indol-3-yl)ethyl)amino)-7-(4-chlorobenzyl)-1-methyl-2,6-dioxo-1,2,6,7-tetrahydro-3H-purin-3-yl)acetonitrile (76) 1, 136.3, 135.8, 132.1, 129.0, 128.5, 127.3, 122.9, 120.9, 118.31, 118.26, 115.7, 111.43, 111.36, 101.3, 44.8, 43.4, 30.6, 27.4, 25.…”

“…,940, ARC, American Radiolabeled Chemicals, St. Louis, MO, USA) in a final concentration of 0.1 nM. 76,78,79 As a source for human CB 1 and CB 2 receptors, membrane preparations of CHO cells stably expressing the respective receptor subtype were employed (30 μg of protein per vial for CB 1 assays, 16 μg of protein per vial for CB 2 receptor assays). Stock solutions of the test compounds were prepared in DMSO.…”

A Tandem Hydroformylation‐Organocatalyzed Friedel‐Crafts Reaction for the Synthesis of Diindolylmethanes

“…I3C is however unstable in aqueous and acidic conditions and converts in vivo to 3,3'-diindolylmethane (DIM), which is the major condensation product and the trigger for cancer cell death of various cancer types. [5,6] DIM and its derivatives are not only used as anti-cancer treatment, but also as fungicides for phytopathogenic fungi, [7] anti-bacterial compounds against phytopathogenic bacteria such as Streptococcus mutans in the oral biofilm, [8] as well as anti-inflammatory as a part of the cannabinoid receptor subtype CB 2 , [9] among others.…”