The two synthetic cannabinoid compounds 4'-F-CBD and HU-910 efficiently restrain inflammatory responses of brain microglia and astrocytes.

To study the anti-inflammatory potential of the two synthetic cannabinoids 4'-F-CBD and HU-910, we used post-natal brain cultures of mouse microglial cells and astrocytes activated by reference inflammogens. We found that 4'-F-CBD and HU-910 efficiently curtailed the release of TNF-α, IL-6, and IL-1ß in microglia and astrocytes activated by the bacterial Toll-Like Receptor (TLR)4 ligand LPS. Upon LPS challenge, 4'-F-CBD and HU-910 also prevented the activation of phenotypic activation markers specific to microglia and astrocytes, that is, Iba-1 and GFAP, respectively. In microglial cells, the two test compounds also efficiently restrained LPS-stimulated release of glutamate, a non-cytokine inflammation marker for these cells. The immunosuppressive effects of the two cannabinoid compounds were concentration-dependent and observable between 1 and 10 µM. These effects were not dependent on cannabinoid or cannabinoid-like receptors. Both 4'-F-CBD and HU-910 were also capable of restraining the inflammogenic activity of Pam3CSK4, a lipopeptide that activates TLR2, and of BzATP, a prototypic agonist of P2X7 purinergic receptors, suggesting that these two cannabinoids could exert immunosuppressive effects against a variety of inflammatory stimuli. Using LPS-stimulated microglia and astrocytes, we established that the immunosuppressive action of 4'-F-CBD and HU-910 resulted from the inhibition of ROS produced by NADPH oxidase and subsequent repression of NF-κB-dependent signaling events. Our results suggest that 4'-F-CBD and HU-910 may have therapeutic utility in pathological conditions where neuroinflammatory processes are prominent.

Cytochrome P450-Catalyzed Metabolism of Cannabidiol to the Active Metabolite 7-Hydroxy-Cannabidiol.

Cannabidiol (CBD) is a naturally occurring nonpsychotoxic phytocannabinoid that has gained increasing attention as a popular consumer product and for its use in Food and Drug Administration-approved Epidiolex (CBD oral solution) for the treatment of Lennox-Gastaut syndrome and Dravet syndrome. CBD was previously reported to be metabolized primarily by CYP2C19 and CYP3A4, with minor contributions from UDP-glucuronosyltransferases. 7-Hydroxy-CBD (7-OH-CBD) is the primary active metabolite with equipotent activity compared with CBD. Given the polymorphic nature of CYP2C19, we hypothesized that variable CYP2C19 expression may lead to interindividual differences in CBD metabolism to 7-OH-CBD. The objectives of this study were to further characterize the roles of cytochrome P450 enzymes in CBD metabolism, specifically to the active metabolite 7-OH-CBD, and to investigate the impact of CYP2C19 polymorphism on CBD metabolism in genotyped human liver microsomes. The results from reaction phenotyping experiments with recombinant cytochrome P450 enzymes and cytochrome P450-selective chemical inhibitors indicated that both CYP2C19 and CYP2C9 are capable of CBD metabolism to 7-OH-CBD. CYP3A played a major role in CBD metabolic clearance via oxidation at sites other than the 7-position. In genotyped human liver microsomes, 7-OH-CBD formation was positively correlated with CYP2C19 activity but was not associated with CYP2C19 genotype. In a subset of single-donor human liver microsomes with moderate to low CYP2C19 activity, CYP2C9 inhibition significantly reduced 7-OH-CBD formation, suggesting that CYP2C9 may play a greater role in CBD 7-hydroxylation than previously thought. Collectively, these data indicate that both CYP2C19 and CYP2C9 are important contributors in CBD metabolism to the active metabolite 7-OH-CBD. SIGNIFICANCE STATEMENT: This study demonstrates that both CYP2C19 and CYP2C9 are involved in CBD metabolism to the active metabolite 7-OH-CBD and that CYP3A4 is a major contributor to CBD metabolism through pathways other than 7-hydroxylation. 7-OH-CBD formation was associated with human liver microsomal CYP2C19 activity, but not CYP2C19 genotype, and CYP2C9 was found to contribute significantly to 7-OH-CBD generation. These findings have implications for patients taking CBD who may be at risk for clinically important cytochrome P450-mediated drug interactions.

O-1602 Promotes Hepatic Steatosis through GPR55 and PI3 Kinase/Akt/SREBP-1c Signaling in Mice.

Non-alcoholic fatty liver disease is recognized as the leading cause of chronic liver disease. Overnutrition and obesity are associated with hepatic steatosis. G protein-coupled receptor 55 (GPR55) has not been extensively studied in hepatic steatosis, although its endogenous ligands have been implicated in liver disease progression. Therefore, the functions of GPR55 were investigated in Hep3B human hepatoma cells and mice fed high-fat diets. O-1602, the most potent agonist of GPR55, induced lipid accumulation in hepatocytes, which was reversed by treatment with CID16020046, an antagonist of GPR55. O-1602 also induced intracellular calcium rise in Hep3B cells in a GPR55-independent manner. O-1602-induced lipid accumulation was dependent on the PI3 kinase/Akt/SREBP-1c signaling cascade. Furthermore, we found increased levels of lysophosphatidylinositol species of 16:0, 18:0, 18:1, 18:2, 20:1, and 20:2 in the livers of mice fed a high-fat diet for 4 weeks. One-week treatment with CID16020046 suppressed high-fat diet-induced lipid accumulation and O-1602-induced increase of serum triglyceride levels in vivo. Therefore, the present data suggest the pro-steatotic function of GPR55 signaling in hepatocytes and provide a potential therapeutic target for non-alcoholic fatty liver disease.

Contribution of the Adenosine 2A Receptor to Behavioral Effects of Tetrahydrocannabinol, Cannabidiol and PECS-101.

The cannabis-derived molecules, ∆9 tetrahydrocannabinol (THC) and cannabidiol (CBD), are both of considerable therapeutic interest for a variety of purposes, including to reduce pain and anxiety and increase sleep. In addition to their other pharmacological targets, both THC and CBD are competitive inhibitors of the equilibrative nucleoside transporter-1 (ENT-1), a primary inactivation mechanism for adenosine, and thereby increase adenosine signaling. The goal of this study was to examine the role of adenosine A2A receptor activation in the effects of intraperitoneally administered THC alone and in combination with CBD or PECS-101, a 4'-fluorinated derivative of CBD, in the cannabinoid tetrad, elevated plus maze (EPM) and marble bury assays. Comparisons between wild-type (WT) and A2AR knock out (A2AR-KO) mice were made. The cataleptic effects of THC were diminished in A2AR-KO; no other THC behaviors were affected by A2AR deletion. CBD (5 mg/kg) potentiated the cataleptic response to THC (5 mg/kg) in WT but not A2AR-KO. Neither CBD nor THC alone affected EPM behavior; their combination produced a significant increase in open/closed arm time in WT but not A2AR-KO. Both THC and CBD reduced the number of marbles buried in A2AR-KO but not WT mice. Like CBD, PECS-101 potentiated the cataleptic response to THC in WT but not A2AR-KO mice. PECS-101 also reduced exploratory behavior in the EPM in both genotypes. These results support the hypothesis that CBD and PECS-101 can potentiate the cataleptic effects of THC in a manner consistent with increased endogenous adenosine signaling.

Cannabinoid Quinones-A Review and Novel Observations.

A cannabinoid anticancer para-quinone, HU-331, which was synthesized by our group five decades ago, was shown to have very high efficacy against human cancer cell lines in-vitro and against in-vivo grafts of human tumors in nude mice. The main mechanism was topoisomerase IIα catalytic inhibition. Later, several groups synthesized related compounds. In the present presentation, we review the publications on compounds synthesized on the basis of HU-331, summarize their published activities and mechanisms of action and report the synthesis and action of novel quinones, thus expanding the structure-activity relationship in these series.

Raman-Based Differentiation of Hemp, Cannabidiol-Rich Hemp, and Cannabis.

Hemp (Cannabis sativa) has been used to treat pain as far back as 2900 B.C. Its pharmacological effects originate from a large variety of cannabinols. Although more than 100 different cannabinoids have been isolated from Cannabis plants, clear physiological effects of only a few of them have been determined, including delta-9 tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabigerol (CBG). While THC is an illicit drug, CBD and CBG are legal substances that have a variety of unique pharmacological properties such as the reduction of chronic pain, inflammation, anxiety, and depression. Over the past decade, substantial efforts have been made to develop Cannabis varieties that would produce large amounts of CBD and CBG. Ideally, such plant varieties should produce very little (below 0.3%) if any THC to make their cultivation legal. The amount of cannabinoids in the plant material can be determined using high performance liquid chromatography (HPLC). This analysis, however, is nonportable, destructive, and time and labor consuming. Our group recently proposed to use Raman spectroscopy (RS) for confirmatory, noninvasive, and nondestructive differentiation between hemp and cannabis. The question to ask is whether RS can be used to detect CBD and CBG in hemp, as well as enable confirmatory differentiation between hemp, cannabis, and CBD-rich hemp. In this manuscript, we show that RS can be used to differentiate between cannabis, CBD-rich plants, and regular hemp. We also report spectroscopic signatures of CBG, cannabigerolic acid (CBGA), THC, delta-9-tetrahydrocannabinolic acid (THCA), CBD, and cannabidiolic acid (CBDA) that can be used for Raman-based quantitative diagnostics of these cannabinoids in plant material.

The Role of Atypical Cannabinoid Ligands O-1602 and O-1918 on Skeletal Muscle Homeostasis with a Focus on Obesity.

O-1602 and O-1918 are atypical cannabinoid ligands for GPR55 and GPR18, which may be novel pharmaceuticals for the treatment of obesity by targeting energy homeostasis regulation in skeletal muscle. This study aimed to determine the effect of O-1602 or O-1918 on markers of oxidative capacity and fatty acid metabolism in the skeletal muscle. Diet-induced obese (DIO) male Sprague Dawley rats were administered a daily intraperitoneal injection of O-1602, O-1918 or vehicle for 6 weeks. C2C12 myotubes were treated with O-1602 or O-1918 and human primary myotubes were treated with O-1918. GPR18 mRNA was expressed in the skeletal muscle of DIO rats and was up-regulated in red gastrocnemius when compared with white gastrocnemius. O-1602 had no effect on mRNA expression on selected markers for oxidative capacity, fatty acid metabolism or adiponectin signalling in gastrocnemius from DIO rats or in C2C12 myotubes, while APPL2 mRNA was up-regulated in white gastrocnemius in DIO rats treated with O-1918. In C2C12 myotubes treated with O-1918, PGC1α, NFATc1 and PDK4 mRNA were up-regulated. There were no effects of O-1918 on mRNA expression in human primary myotubes derived from obese and obese T2DM individuals. In conclusion, O-1602 does not alter mRNA expression of key pathways important for skeletal muscle energy homeostasis in obesity. In contrast, O-1918 appears to alter markers of oxidative capacity and fatty acid metabolism in C2C12 myotubes only. GPR18 is expressed in DIO rat skeletal muscle and future work could focus on selectively modulating GPR18 in a tissue-specific manner, which may be beneficial for obesity-targeted therapies.

A Novel Alternative in the Treatment of Detrusor Overactivity? In Vivo Activity of O-1602, the Newly Synthesized Agonist of GPR55 and GPR18 Cannabinoid Receptors.

The aim of the research was to assess the impact of O-1602-novel GPR55 and GPR18 agonist-in the rat model of detrusor overactivity (DO). Additionally, its effect on the level of specific biomarkers was examined. To stimulate DO, 0.75% retinyl acetate (RA) was administered to female rats' bladders. O-1602, at a single dose of 0.25 mg/kg, was injected intra-arterially during conscious cystometry. Furthermore, heart rate, blood pressure, and urine production were monitored for 24 h, and the impact of O-1602 on the levels of specific biomarkers was evaluated. An exposure of the urothelium to RA changed cystometric parameters and enhanced the biomarker levels. O-1602 did not affect any of the examined cystometric parameters or levels of biomarkers in control rats. However, the O-1602 injection into animals with RA-induced DO ameliorated the symptoms of DO and caused a reversal in the described changes in the concentration of CGRP, OCT3, BDNF, and NGF to the levels observed in the control, while the values of ERK1/2 and VAChT were significantly lowered compared with the RA-induced DO group, but were still statistically higher than in the control. O-1602 can improve DO, and may serve as a promising novel substance for the pharmacotherapy of bladder diseases.

DMH-CBD, a cannabidiol analog with reduced cytotoxicity, inhibits TNF production by targeting NF-kB activity dependent on A2A receptor.

Cannabidiol (CBD) is a natural compound with psychoactive therapeutic properties well described. Conversely, the immunological effects of CBD are still poorly explored. In this study, the potential anti-inflammatory effects and underlying mechanisms of CBD and its analog Dimethyl-Heptyl-Cannabidiol (DMH-CBD) were investigated using RAW 264.7 macrophages. CBD and DMH-CBD suppressed LPS-induced TNF production and NF-kB activity in a concentration-dependent manner. Both compounds reduced the NF-kB activity in a µM concentration range: CBD (IC50 = 15 µM) and DMH-CBD (IC50 = 38 µM). However, the concentrations of CBD that mediated NF-kB inhibition were similar to those that cause cytotoxicity (LC50 = 58 µM). Differently, DMH-CBD inhibited the NF-kB activation without cytotoxic effects at the same concentrations, although it provokes cytotoxicity at long-term exposure. The inhibitory action of the DMH-CBD on NF-kB activity was not related to the reduction in IkBα degradation or either p65 (NF-kB) translocation to the nucleus, although it decreased p38 MAP kinase phosphorylation. Additionally, 8-(3-Chlorostyryl) caffeine (CSC), an A2A antagonist, reversed the effect of DMH-CBD on NF-kB activity in a concentration-dependent manner. Collectively, our results demonstrated that CBD reduces NF-kB activity at concentrations intimately associated with those that cause cell death, whereas DMH-CBD decreases NF-kB activity at non-toxic concentrations in an A2A receptor dependent-manner.

Activation of GPR55 induces neuroprotection of hippocampal neurogenesis and immune responses of neural stem cells following chronic, systemic inflammation.

New neurons are continuously produced by neural stem cells (NSCs) within the adult hippocampus. Numerous diseases, including major depressive disorder and HIV-1 associated neurocognitive disorder, are associated with decreased rates of adult neurogenesis. A hallmark of these conditions is a chronic release of neuroinflammatory mediators by activated resident glia. Recent studies have shown a neuroprotective role on NSCs of cannabinoid receptor activation. Yet, little is known about the effects of GPR55, a candidate cannabinoid receptor, activation on reductions of neurogenesis in response to inflammatory insult. In the present study, we examined NSCs exposed to IL-1ß in vitro to assess inflammation-caused effects on NSC differentiation and the ability of GPR55 agonists to attenuate NSC injury. NSC differentiation and neurogenesis was determined via immunofluorescence and flow cytometric analysis of NSC markers (Nestin, Sox2, DCX, S100ß, ßIII Tubulin, GFAP). GPR55 agonist treatment protected against IL-1ß induced reductions in neurogenesis rates. Moreover, inflammatory cytokine receptor mRNA expression was down regulated by GPR55 activation in a neuroprotective manner. To determine inflammatory responses in vivo, we treated C57BL/6 and GPR55-/- mice with LPS (0.2 mg/kg/day) continuously for 14 days via osmotic mini-pump. Reductions in NSC survival (as determined by BrdU incorporation), immature neurons, and neuroblast formation due to LPS were attenuated by concurrent direct intrahippocampal administration of the GPR55 agonist, O-1602 (4 µg/kg/day). Molecular analysis of the hippocampal region showed a suppressed ability to regulate immune responses by GPR55-/- animals manifesting in a prolonged inflammatory response (IL-1ß, IL-6, TNFα) after chronic, systemic inflammation as compared to C57BL/6 animals. Taken together, these results suggest a neuroprotective role of GPR55 activation on NSCs in vitro and in vivo and that GPR55 provides a novel therapeutic target against negative regulation of hippocampal neurogenesis by inflammatory insult.

Comparison of the effect of three different topoisomerase II inhibitors combined with cisplatin in human glioblastoma cells sensitized with double strand break repair inhibitors.

Topoisomerase II (Topo2) inhibitors in combination with cisplatin represent a common treatment modality used for glioma patients. The main mechanism of their action involves induction of DNA double-strand breaks (DSBs). DSBs are repaired via the homology-dependent DNA repair (HRR) and non-homologous end-joining (NHEJ). Inhibition of the NHEJ or HRR pathway sensitizes cancer cells to the treatment. In this work, we investigated the effect of three Topo2 inhibitors-etoposide, NK314, or HU-331 in combination with cisplatin in the U-87 human glioblastoma cell line. Etoposide as well as NK314 inhibited Topo2 activity by stabilizing Topo2-DNA cleavable complexes whereas HU-331 inhibited the ATPase activity of Topo2 using a noncompetitive mechanism. To increase the effectiveness of the treatment, we combined cisplatin and Topo2 inhibitor treatment with DSB repair inhibitors (DRIs). The cells were sensitized with NHEJ inhibitor, NU7441, or the novel HRR inhibitor, YU238259, prior to drug treatment. All of the investigated Topo2 inhibitors in combination with cisplatin efficiently killed the U-87 cells. The most cytotoxic effect was observed for the cisplatin + HU331 treatment scheme and this effect was significantly increased when a DRI pretreatment was used; however, we did not observed DSBs. Therefore, the molecular mechanism of cytotoxicity caused by the cisplatin + HU331 treatment scheme is yet to be evaluated. We observed a concentration-dependent change in DSB levels and accumulation at the G2/M checkpoint and S-phase in glioma cells incubated with NK314/cisplatin and etoposide/cisplatin. In conclusion, in combination with cisplatin, HU331 is the most potent Topo2 inhibitor of human glioblastoma cells.

HU-331 and Oxidized Cannabidiol Act as Inhibitors of Human Topoisomerase IIα and ß.

Topoisomerase II is a critical enzyme in replication, transcription, and the regulation of chromatin topology. Several anticancer agents target topoisomerases in order to disrupt cell growth. Cannabidiol is a major non-euphoriant, pharmacologically active component of cannabis. Previously, we examined the cannabidiol derivative HU-331 in order to characterize the mechanism of the compound against topoisomerase IIα. In this current work, we explore whether cannabidiol (CBD) impacts topoisomerase II activity, and we additionally examine the activity of these compounds against topoisomerase IIß. CBD does not appear to strongly inhibit DNA relaxation and is not a poison of topoisomerase II DNA cleavage. However, oxidation of CBD allows this compound to inhibit DNA relaxation by topoisomerase IIα and ß without poisoning DNA cleavage. Additionally, we found that oxidized CBD, similar to HU-331, inhibits ATP hydrolysis and can result in inactivation of topoisomerase IIα and ß. We also determined that oxidized CBD and HU-331 are both able to stabilize the N-terminal clamp of topoisomerase II. Taken together, we conclude that while CBD does not have significant activity against topoisomerase II, both oxidized CBD and HU-331 are active against both isoforms of topoisomerase II. We hypothesize that oxidized CBD and HU-331 act against the enzyme through interaction with the N-terminal ATPase domain. According to the model we propose, topoisomerase II inactivation may result from a decrease in the ability of the enzyme to bind to DNA when the compound is bound to the N-terminus.

The cation channel Trpv2 is a new suppressor of arthritis severity, joint damage, and synovial fibroblast invasion.

Little is known about the regulation of arthritis severity and joint damage in rheumatoid arthritis (RA). Fibroblast-like synoviocytes (FLS) have a central role in joint damage and express increased levels of the cation channel Trpv2. We aimed at determining the role of Trpv2 in arthritis. Treatment with Trpv2-specific agonists decreased the in vitro invasiveness of FLS from RA patients and arthritic rats and mice. Trpv2 stimulation suppressed IL-1ß-induced expression of MMP-2 and MMP-3. Trpv2 agonists, including the new and more potent LER13, significantly reduced disease severity in KRN serum- and collagen-induced arthritis, and reduced histologic joint damage, synovial inflammation, and synovial blood vessel numbers suggesting anti-angiogenic activity. In this first in vivo use of Trpv2 agonists we discovered a new central role for Trpv2 in arthritis. These new compounds have the potential to become new therapies for RA and other diseases associated with inflammation, invasion, and angiogenesis.

Enantioselective total syntheses of (+)-hostmanin A, (-)-linderol A, (+)-methyllinderatin and structural reassignment of adunctin E.

A one-step protocol has been developed for the enantioselective synthesis of hexahydrodibenzofuran derivatives using a modified Friedel-Crafts reaction. The developed method was applied to the synthesis of a series of natural products including (+)-hostmanin A, (+)-methyllinderatin, and (-)-linderol A. The synthetic and spectroscopic data investigations led to the structural reassignment of natural product adunctin E, which was further confirmed by single-crystal X-ray analysis.

Cannabidiol (CBD) and its analogs: a review of their effects on inflammation.

First isolated from Cannabis in 1940 by Roger Adams, the structure of CBD was not completely elucidated until 1963. Subsequent studies resulted in the pronouncement that THC was the 'active' principle of Cannabis and research then focused primarily on it to the virtual exclusion of CBD. This was no doubt due to the belief that activity meant psychoactivity that was shown by THC and not by CBD. In retrospect this must be seen as unfortunate since a number of actions of CBD with potential therapeutic benefit were downplayed for many years. In this review, attention will be focused on the effects of CBD in the broad area of inflammation where such benefits seem likely to be developed. Topics covered in this review are; the medicinal chemistry of CBD, CBD receptor binding involved in controlling Inflammation, signaling events generated by CBD, downstream events affected by CBD (gene expression and transcription), functional effects reported for CBD and combined THC plus CBD treatment.

HU-331 is a catalytic inhibitor of topoisomerase IIα.

Topoisomerases are essential enzymes that are involved in DNA metabolism. Topoisomerase II generates transient DNA strand breaks that are stabilized by anticancer drugs, such as doxorubicin, causing an accumulation of DNA damage. However, doxorubicin causes cardiac toxicity and, like etoposide and other topoisomerase II-targeted agents, can induce DNA damage, resulting in secondary cancers. The cannabinoid quinone HU-331 has been identified as a potential anticancer drug that demonstrates more potency in cancer cells with less off-target toxicity than that of doxorubicin. Reports indicate that HU-331 does not promote cell death via apoptosis, cell cycle arrest, caspase activation, or DNA strand breaks. However, the precise mechanism of action is poorly understood. We employed biochemical assays to study the mechanism of action of HU-331 against purified topoisomerase IIα. These assays examined DNA binding, cleavage, ligation, relaxation, and ATPase activities of topoisomerase IIα. Our results demonstrate that HU-331 inhibits topoisomerase IIα-mediated DNA relaxation at micromolar levels. We find that HU-331 does not induce DNA strand breaks in vitro. When added prior to the DNA substrate, HU-331 blocks DNA cleavage and relaxation activities of topoisomerase IIα in a redox-sensitive manner. The action of HU-331 can be blocked, but not reversed, by the presence of dithiothreitol. Our results also show that HU-331 inhibits the ATPase activity of topoisomerase IIα using a noncompetitive mechanism. Preliminary binding studies also indicate that HU-331 decreases the ability of topoisomerase IIα to bind DNA. In summary, HU-331 inhibits relaxation activity without poisoning DNA cleavage. This action is sensitive to reducing agents and appears to involve noncompetitive inhibition of the ATPase activity and possibly inhibition of DNA binding. These studies provide a promising foundation for the exploration of HU-331 as a catalytic inhibitor of topoisomerase IIα.

Atropisomerism about aryl-Csp(3) bonds: the electronic and steric influence of ortho-substituents on conformational exchange in cannabidiol and linderatin derivatives.

Terpenylation reactions of substituted phenols were used to prepare cannabidiol and linderatin derivatives, and their structure and conformational behavior in solution were investigated by NMR and, for some representative examples, by DFT. VT-NMR spectra and DFT calculations were used to determine the activation energies of the conformational change arising from restricted rotation about the aryl-Csp(3) bond that lead to two unequally populated rotameric epimers. The NBO calculation was applied to explain the electronic stabilization of one conformer over another by donor-acceptor charge transfer interactions. Conformational control arises from a combination of stereoelectronic and steric effects between substituents in close contact with each other on the two rings of the endocyclic epoxide atropisomers. This study represents the first exploration of the stereoelectronic origins of atropisomerism around C(sp(2))-C(sp(3)) single bonds through theoretical calculations.

Chemistry and pharmacological aspects of furanoid cannabinoids and related compounds: Is furanoid cannabinoids open a new dimension towards the non-psychoactive cannabinoids?

Cannabinoids have emerged as compelling candidates for medicinal applications, notably following the recent approval of non-psychoactive cannabidiol (CBD) as a medicine. This endorsement has stimulated a growing interest in this class of compounds for drug discovery. Within the cannabis plant, a rich reservoir of over 125 compounds exists. Tetrahydrocannabinol (THC), a member of the dibenzopyran class, is widely recognized for its psychoactive effects. Conversely, the furanoid class, represented by cannabielsoin-type (CBE) and cannabifuran-type (CBF) compounds, has not been reported with psychoactivity and demonstrates a spectrum of pharmacological potential. The transition from the pyran structure of THC to the furan structure of CBE seems to mark a shift from psychoactive to non-psychoactive properties, but a comprehensive examination of other members in this class is essential for a complete understanding. Building on these observations, our thorough review delves into the subject, offering a comprehensive exploration of furanoid cannabinoids, covering aspects such as their biosynthesis, classification, synthesis, and medicinal potential. The aim of this review is to encourage and catalyze increased research focus in this promising area of cannabinoid exploration.

Library Screening and Preliminary Characterization of Synthetic Cannabinoids Against Prostate and Pancreatic Cancer Cell Lines.

Background: Our previous screening efforts with colorectal cancer cell lines suggested potential cannabinoid therapeutic leads for other solid cancers. Objectives: The aim of this study was to identify cannabinoid lead compounds that have cytostatic and cytocidal activities against prostate and pancreatic cancer cell lines and profile cellular responses and molecular pathways of select leads. Materials and Methods: A library of 369 synthetic cannabinoids was screened against 4 prostate and 2 pancreatic cancer cell lines with 48 h of exposure at 10 µM in medium with 10% fetal bovine serum using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) viability assay. Concentration titration of the top 6 hits was carried out to identify their concentration-response patterns and calculate IC50 values. Three select leads were examined for cell cycle, apoptosis, and autophagy responses. The role of cannabinoid receptors (CB1 and CB2) and noncanonical receptors in apoptosis signaling was examined with selective antagonists. Results: Two independent screening experiments in each cell line detected growth inhibitory activities against all six or a majority of cancer cell lines for HU-331 (a known cannabinoid topoisomerase II inhibitor), (±)5-epi-CP55,940, and PTI-2, each previously identified in our colorectal cancer study. 5-Fluoro NPB-22, FUB-NPB-22, and LY2183240 were novel hits. Morphologically and biochemically, (±)5-epi-CP55,940 elicited caspase-mediated apoptosis of PC-3-luc2 (a PC-3 subline with luciferase) prostate cancer and Panc-1 pancreatic cancer cell lines, each the most aggressive of the respective organ site. The apoptosis induced by (±)5-epi-CP55,940 was abolished by the CB2 antagonist, SR144528, but not modulated by the CB1 antagonist, rimonabant, and GPR55 antagonist, ML-193, nor TRPV1 antagonist, SB-705498. In contrast, 5-fluoro NPB-22 and FUB-NPB-22 did not cause substantial apoptosis in either cell line, but resulted in cytosolic vacuoles and increased LC3-II formation (suggestive of autophagy) and S and G2/M cell cycle arrests. Combining each fluoro compound with an autophagy inhibitor, hydroxychloroquine, enhanced the apoptosis. Conclusions: 5-Fluoro NPB-22, FUB-NPB-22, and LY2183240 represent new leads against prostate and pancreatic cancer cells in addition to the previously reported compounds, HU-331, (±)5-epi-CP55,940, and PTI-2. Mechanistically, the two fluoro compounds and (±)5-epi-CP55,940 differed regarding their structures, CB receptor involvement, and death/fate responses and signaling. Safety and antitumor efficacy studies in animal models are warranted to guide further R&D.