Fenchone Derivatives as a Novel Class of CB2 Selective Ligands: Design, Synthesis, X-ray Structure and Therapeutic Potential.

A series of novel cannabinoid-type derivatives were synthesized by the coupling of (1S,4R)-(+) and (1R,4S)-(-)-fenchones with various resorcinols/phenols. The fenchone-resorcinol derivatives were fluorinated using Selectfluor and demethylated using sodium ethanethiolate in dimethylformamide (DMF). The absolute configurations of four compounds were determined by X-ray single crystal diffraction. The fenchone-resorcinol analogs possessed high affinity and selectivity for the CB2 cannabinoid receptor. One of the analogues synthesized, 2-(2',6'-dimethoxy-4'-(2″-methyloctan-2″-yl)phenyl)-1,3,3-trimethylbicyclo[2.2.1]heptan-2-ol (1d), had a high affinity (Ki = 3.51 nM) and selectivity for the human CB2 receptor (hCB2). In the [35S]GTPγS binding assay, our lead compound was found to be a highly potent and efficacious hCB2 receptor agonist (EC50 = 2.59 nM, E(max) = 89.6%). Two of the fenchone derivatives were found to possess anti-inflammatory and analgesic properties. Molecular-modeling studies elucidated the binding interactions of 1d within the CB2 binding site.

HU-444, a Novel, Potent Anti-Inflammatory, Nonpsychotropic Cannabinoid.

Cannabidiol (CBD) is a component of cannabis, which does not cause the typical marijuana-type effects, but has a high potential for use in several therapeutic areas. In contrast to Δ(9)-tetrahydrocannabinol (Δ(9)-THC), it binds very weakly to the CB1 and CB2 cannabinoid receptors. It has potent activity in both in vitro and in vivo anti-inflammatory assays. Thus, it lowers the formation of tumor necrosis factor (TNF)-α, a proinflammatory cytokine, and was found to be an oral antiarthritic therapeutic in murine collagen-induced arthritis in vivo. However, in acidic media, it can cyclize to the psychoactive Δ(9)-THC. We report the synthesis of a novel CBD derivative, HU-444, which cannot be converted by acid cyclization into a Δ(9)-THC-like compound. In vitro HU-444 had anti-inflammatory activity (decrease of reactive oxygen intermediates and inhibition of TNF-α production by macrophages); in vivo it led to suppression of production of TNF-α and amelioration of liver damage as well as lowering of mouse collagen-induced arthritis. HU-444 did not cause Δ(9)-THC-like effects in mice. We believe that HU-444 represents a potential novel drug for rheumatoid arthritis and other inflammatory diseases.

An evaluation of the anti-hyperalgesic effects of cannabidiolic acid-methyl ester in a preclinical model of peripheral neuropathic pain.

BACKGROUND AND PURPOSE: Chronic neuropathic pain (NEP) is associated with growing therapeutic cannabis use. To promote quality of life without psychotropic effects, cannabinoids other than Δ9-tetrahydrocannabidiol, including cannabidiol and its precursor cannabidiolic acid (CBDA), are being evaluated. Due to its instability, CBDA has been understudied, particularly as an anti-nociceptive agent. Adding a methyl ester group (CBDA-ME) significantly enhances its stability, facilitating analyses of its analgesic effects in vivo. This study examines early treatment efficacy of CBDA-ME in a rat model of peripherally induced NEP and evaluates sex as a biological variable. EXPERIMENTAL APPROACH: After 14 consecutive days of intraperitoneal CBDA-ME administration at 0.01, 0.1 and 1 µg·kg-1 , commencing 1 day after surgically implanting a sciatic nerve-constricting cuff to induce NEP, the anti-nociceptive efficacy of this cannabinoid was assessed in male and female Sprague-Dawley rats relative to vehicle-treated counterparts. In females, 2 and 4 µg·kg-1 daily doses of CBDA-ME were also evaluated. Behavioural tests were performed for hind paw mechanical and thermal withdrawal thresholds once a week for 8 weeks. At endpoint, in vivo electrophysiological recordings were obtained to characterize soma threshold changes in primary sensory neurons. KEY RESULTS: In males, CBDA-ME elicited a significant concentration-dependent chronic anti-hyperalgesic effect, also influencing both nociceptive and non-nociceptive mechanoreceptors, which were not observed in females at any of the concentrations tested. CONCLUSION AND IMPLICATIONS: Initiating treatment of a peripheral nerve injury with CBDA-ME at an early stage post-surgery provides anti-nociception in males, warranting further investigation into potential sexual dimorphisms underlying this response.

Cannabidiolic acid methyl ester, a stable synthetic analogue of cannabidiolic acid, can produce 5-HT1A receptor-mediated suppression of nausea and anxiety in rats.

BACKGROUND AND PURPOSE: The aim of this study was to compare the abilities of cannabidiolic acid methyl ester (HU-580) and cannabidiolic acid (CBDA) to enhance 5-HT1A receptor activation in vitro and produce 5-HT1A -mediated reductions in nausea and anxiety in vivo. EXPERIMENTAL APPROACH: We investigated the effects of HU-580 and CBDA on (i) activation by 8-hydroxy-2-(di-n-propylamino)tetralin of human 5-HT1A receptors in CHO cell membranes, using [35 S]-GTPγS binding assays, (ii) gaping by rats in acute and anticipatory nausea models, and (iii) stress-induced anxiety-like behaviour, as indicated by exit time from the light compartment of a light-dark box of rats subjected 24 h earlier to six tone-paired foot shocks. KEY RESULTS: HU-580 and CBDA increased the Emax of 8-hydroxy-2-(di-n-propylamino) tetralin in vitro at 0.01-10 and 0.1-10 nM, respectively, and reduced signs of (i) acute nausea at 0.1 and 1 µg·kg-1 i.p. and at 1 µg·kg-1 i.p., respectively, and (ii) anticipatory nausea at 0.01 and 0.1 µg·kg-1 , and at 0.1 µg·kg-1 i.p. respectively. At 0.01 µg·kg-1 , HU-580, but not CBDA, increased the time foot-shocked rats spent in the light compartment of a light-dark box. The anti-nausea and anti-anxiety effects of 0.01 or 0.1 µg·kg-1 HU-580 were opposed by the 5-HT1A antagonist, WAY100635 (0.1 mg·kg-1 i.p.). CONCLUSIONS AND IMPLICATIONS: HU-580 is more potent than CBDA at enhancing 5-HT1A receptor activation, and inhibiting signs of acute and anticipatory nausea, and anxiety. Consequently, HU-580 is a potential medicine for treating some nausea and anxiety disorders and possibly other disorders ameliorated by enhancement of 5-HT1A receptor activation.

Acute oral cannabidiolic acid methyl ester reduces depression-like behavior in two genetic animal models of depression.

BACKGROUND AND PURPOSE: Cannabidiolic acid methyl ester (HU-580) was recently shown to reduce stress-induced anxiety-like behavior in rats. The aim of this study was to examine the antidepressant effect of HU-580 in two different rat models of depression. EXPERIMENTAL APPROACH: Using the forced swim test (FST), we evaluated the effect of HU-580 in 43 Wistar-Kyoto (WKY) and 23 Flinders Sensitive Line (FSL) adult male rats. KEY RESULTS: 1 mg/kg HU-580 reduced immobility and increased swimming in WKY rats, compared to vehicle-treated controls (p < 0.05). This dose exerted similar effects in FSL rats (p < 0.05). CONCLUSION AND IMPLICATIONS: This is the first report of antidepressant efficacy of HU-580. These findings expand the very limited existent results, suggesting that HU-580 is a potent anxiolytic agent. Taken together with its chemical stability, HU-580 emerges as a candidate for a future antidepressant medication.

HU-446 and HU-465, Derivatives of the Non-psychoactive Cannabinoid Cannabidiol, Decrease the Activation of Encephalitogenic T Cells.

Cannabidiol (CBD), the non-psychoactive cannabinoid, has been previously shown by us to decrease peripheral inflammation and neuroinflammation in mouse experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis (MS). Here we have studied the anti-inflammatory effects of newly synthesized derivatives of natural (-)-CBD ((-)-8,9-dihydro-7-hydroxy-CBD; HU-446) and of synthetic (+)-CBD ((+)-8,9-dihydro-7-hydroxy-CBD; HU-465) on activated myelin oligodendrocyte glycoprotein (MOG)35-55-specific mouse encephalitogenic T cells (T(MOG) ) driving EAE/MS-like pathologies. Binding assays followed by molecular modeling revealed that HU-446 has negligible affinity toward the cannabinoid CB1 and CB2 receptors while HU-465 binds to both CB1 and CB2 receptors at the high nanomolar concentrations (Ki = 76.7 ± 5.8 nm and 12.1 ± 2.3 nm, respectively). Both, HU-446 and HU-465, at 5 and 10 µm (but not at 0.1 and 1 µm), inhibited the MOG35-55-induced proliferation of autoreactive T(MOG) cells via CB1/CB2 receptor independent mechanisms. Moreover, both HU-446 and HU-465, at 5 and 10 µm, inhibited the release of IL-17, a key autoimmune cytokine, from MOG35-55-stimulated T(MOG) cells. These results suggest that HU-446 and HU-465 have anti-inflammatory potential in inflammatory and autoimmune diseases.

Fluorinated Cannabidiol Derivatives: Enhancement of Activity in Mice Models Predictive of Anxiolytic, Antidepressant and Antipsychotic Effects.

Cannabidiol (CBD) is a major Cannabis sativa constituent, which does not cause the typical marijuana psychoactivity. However, it has been shown to be active in a numerous pharmacological assays, including mice tests for anxiety, obsessive-compulsive disorder, depression and schizophrenia. In human trials the doses of CBD needed to achieve effects in anxiety and schizophrenia are high. We report now the synthesis of 3 fluorinated CBD derivatives, one of which, 4'-F-CBD (HUF-101) (1), is considerably more potent than CBD in behavioral assays in mice predictive of anxiolytic, antidepressant, antipsychotic and anti-compulsive activity. Similar to CBD, the anti-compulsive effects of HUF-101 depend on cannabinoid receptors.

Correction: Fluorinated Cannabidiol Derivatives: Enhancement of Activity in Mice Models Predictive of Anxiolytic, Antidepressant and Antipsychotic Effects.

[This corrects the article DOI: 10.1371/journal.pone.0158779.].