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The endocannabinoid system consists of endocannabinoids, cannabinoid receptors and enzymes that synthesise and degrade the endocannabinoids. The cannabinoid receptors (CBR) are an important class of receptors participating in various physiological processes. Many of their effects are mediated by two G protein-coupled receptors (GPCRs), (CB1) and (CB2), although additional receptors may be involved. The purpose of this paper is to present a computer modelling of the CBR and several known cannabinoid ligands aiming to determine the structure-activity relationship by using molecular docking with GOLD software. Four scoring functions provided by GOLD are used for molecular docking of the models of CBR1, its crystal structure and the known cannabinoid ligands. Significant correlations between the biological activity of the ligands and the ChemScore optimization function are established. The results obtained could be further used for in silico experiments of the interaction between CBR and cannabinoid ligands. [ABSTRACT FROM AUTHOR]

Abnormal cannabidiol (abn-CBD) exerts neuroprotective effects in vivo and in vitro. In the present study, we investigated the impact of abn-CBD on the glial production of proinflammatory mediators and scar formation within in vitro models. Primary astrocytic-microglial cocultures and astrocytic cultures from neonatal C57BL/6 mice and CB2 receptor knockout mice were stimulated with lipopolysaccharide (LPS), and the concentrations of tumor necrosis factor α (TNFα), interleukin-6 (IL-6) and nitrite were determined. Furthermore, we performed a live cell microscopy-based scratch-wound assay. After LPS stimulation, TNFα, IL-6 and nitrite production was more strongly increased in cocultures than in isolated astrocytes. Abn-CBD treatment attenuated the LPS-induced production of TNFα and nitrite in cocultures, while IL-6 production remained unaltered. In isolated astrocytes, only LPS-induced TNFα production was reduced by abn-CBD. Similar effects were observed after abn-CBD application in cocultures of CB2 knockout mice. Interestingly, LPS-induced TNFα and nitrite levels were far lower in CB2 knockout cultures compared to wildtypes, while IL-6 levels did not differ. In the scratch-wound assay, treatment with abn-CBD decelerated wound closure when microglial cells were present. Our data shows a differential role of abn-CBD for modulation of glial inflammation and astrocytic scar formation. These findings provide new explanations for mechanisms behind the neuroprotective potential of abn-CBD.

The endocannabinoid system (ECS) is abundantly expressed in the brain. This system regulates a plethora of physiological functions and is composed of cannabinoid receptors, their endogenous ligands (endocannabinoids), and the enzymes involved in the metabolism of endocannabinoids. In this review, we highlight the new advances in cannabinoid signaling, focusing on a key component of the ECS, the type-1 cannabinoid receptor (CB 1). In recent years, the development of new imaging and molecular tools has demonstrated that this receptor can be distributed in many cell types (e.g., neuronal or glial cells) and intracellular compartments (e.g., mitochondria). Interestingly, cellular and molecular effects are differentially mediated by CB 1 receptors according to their specific localization (e.g., glutamatergic or GABAergic neurons). Moreover, this receptor is expressed in the periphery, where it can modulate periphery-brain connections. Finally, the better understanding of the CB 1 receptor structure led researchers to propose interesting and new allosteric modulators. Thus, the advances and the new directions of the CB 1 receptor field will provide new insights and better approaches to profit from its interesting therapeutic profile.

Recent decades have seen much progress in the identification and characterization of cannabinoid receptors and the elucidation of the mechanisms by which derivatives of the Cannabis sativa plant bind to receptors and produce their physiological and psychological effects. The information generated in this process has enabled better understanding of the fundamental physiological and psychological processes controlled by the central and peripheral nervous systems and has fostered the development of natural and synthetic cannabinoids as therapeutic agents. A negative aspect of this decades-long effort is the proliferation of clandestinely synthesized analogs as recreational street drugs with dangerous effects. Currently, the interactions of cannabinoids with their biochemical substrates are extensively but inadequately understood, and the clinical application of derived and synthetic receptor ligands remains quite limited. The wide anatomical distribution and functional complexity of the cannabinoid system continue to indicate potential for both therapeutic and side effects, which offers challenges and opportunities for medicinal chemists involved in drug discovery and development. [ABSTRACT FROM AUTHOR]

In our ongoing program aimed at deeply investigating the endocannabinoid system (ES), a set of new alkyl-resorcinol derivatives was prepared focusing on the nature and the importance of the carboxamide functionality. Binding studies on CB 1 and CB 2 receptors, monoacylglycerol lipase (MAGL) and fatty acid amide hydrolase (FAAH) showed that some of the newly developed compounds behaved as very potent cannabinoid receptor ligands ( K i in the nanomolar range) while, however, none of them was able to inhibit MAGL and/or FAAH. Derivative 11 was a potent CB 1 and CB 2 ligand, with K i values similar to WIN 55,212, exhibiting a CB 1 and CB 2 agonist profile in vitro. In the formalin test of peripheral acute and inflammatory pain in mice, this compound showed a weak and delayed antinociceptive effect against the second phase of the nocifensive response, exhibiting, interestingly, a quite potent transient receptor potential ankyrin type-1 (TRPA1) channel agonist activity. Moreover, derivative 14 , characterized by lower affinity but higher CB 2 selectivity than 11 , proved to behave as a weak CB 2 competitive inverse agonist. [ABSTRACT FROM AUTHOR]

Abstract: Within our studies on structure–activity relationships of 4-quinolone-3-carboxamides as cannabinoid ligands, a new series of compounds characterized by a fluoro or phenylthio group at 7-position and different substituents at N1 and carboxamide nitrogen were synthesized and evaluated for their binding ability to cannabinoid type 1 (CB1) and type 2 (CB2) receptors. Most of the compounds showed affinity for one or both cannabinoid receptors at nanomolar concentration, with K i(CB1) and K i(CB2) values ranging from 2.45 to >10,000 nM and from 0.09 to 957 nM, respectively. The N-(3,4-dichlorobenzyl)amide derivatives 27 and 40 displayed relatively low affinity, but high selectivity towards the CB1 receptor. Compounds 4 and 40, a CB2 and a CB1 ligand, respectively, behaved as partial agonists in the [35S]GTPγS assay. They showed very low permeability through (MDCK-MDR1) cells and might, therefore, represent possible lead structures for further optimization in the search for cannabinoid ligands unable to cross the blood–brain barrier. [Copyright &y& Elsevier]

Abstract: We present here the pharmacological characterization of cannabinoid-binding sites in zebrafish brain homogenates using radiolabeled binding techniques. The nonselective agonist [3H]-CP55940 binds with high affinity (K D =0.50±0.06nM and a B max =1047±36.01fmol/mg protein), displaying one binding site. The slightly CB2 selective agonist [3H]-WIN55212-2 also binds with high affinity to zebrafish brain membranes displaying two different binding sites with affinities K D1 =0.35±0.09nM and K D2 =105.81±66.36nM. Competition binding assays using [3H]-WIN55212-2 and several unlabeled ligands were performed. WIN55212-2 significantly displaced the tritiated ligand binding showing the two binding sites observed with its tritiated homologous, while the slightly selective CB1 cannabinoid ligand HU-210, the nonselective cannabinoid ligand CP55940 and the endogenous cannabinoid ligand anandamide presented one binding site. Also, the functionality of these cannabinoid sites was analyzed using the known [35S]GTPγS assay. All the agonist used presented an agonist profile and the rank order for potency was HU-210>WIN55212-2>CP55940>anandamide. Our results provide evidence that, although some of the typical cannabinoid ligands for mammalian receptors do not fully recognize the cannabinoid-binding sites in zebrafish brain, the activity of the endogenous zebrafish cannabinoid system might not significantly differ from that displayed by the cannabinoid system described in other species. Hence the study of zebrafish cannabinoid activity may contribute to an understanding of the endogenous cannabinoid system in higher vertebrates. [Copyright &y& Elsevier]

Keywords: cancer; cannabinoid receptors (CB1 and CB2); ECS endocannabinoid system; pain; cannabinoid ligands The endocannabinoid system (ECS) comprises the canonical receptor subtypes CB1R and CB2R and endocannabinoids (anandamide, AEA and 2-arachidonoylglycerol, 2-AG), and a "non-canonical" extended signaling network consisting of: (i) other fatty acid derivatives; (ii) the defined "ionotropic cannabinoid receptors" (TRP channels); other GPCRs (GPR55, PPAR ); (iii) enzymes involved in the biosynthesis and degradation of endocannabinoids (FAAH and MAGL); and (iv) protein transporters (FABP family) ([12]; [6]).The ECS is currently a hot topic due to its involvement in cancer and pain. The authors highlight the regulation of the two canonical receptor subtypes CB1R and CB2R in malignant tissue, emphasizing the involvement in cancer onset and progression of the biosynthetic and degradation enzymes. Cancer, cannabinoid receptors (CB1 and CB2), ECS endocannabinoid system, pain, cannabinoid ligands. [Extracted from the article]

Abstract: A small library of N-benzyl indolequinuclidinone (IQD) analogs has been identified as a novel class of cannabinoid ligands. The affinity and selectivity of these IQDs for the two established cannabinoid receptor subtypes, CB1 and CB2, was evaluated. Compounds 8 (R=R2 =H, R1 =F) and 13 (R=COOCH3, R1 =R2 =H) exhibited high affinity for CB2 receptors with K i values of 1.33 and 2.50nM, respectively, and had lower affinities for the CB1 receptor (K i values of 9.23 and 85.7nM, respectively). Compound 13 had the highest selectivity of all the compounds examined, and represents a potent cannabinoid ligand with 34-times greater selectivity for CB2R over CB1R. These findings are significant for future drug development, given recent reports demonstrating beneficial use of cannabinoid ligands in a wide variety of human disease states including drug abuse, depression, schizophrenia, inflammation, chronic pain, obesity, osteoporosis and cancer. [Copyright &y& Elsevier]

A series of N -benzyl-7-azaindolequinuclidinone (7-AIQD) analogs have been synthesized and evaluated for affinity toward CB1 and CB2 cannabinoid receptors and identified as a novel class of cannabinoid receptor ligands. Structure–activity relationship (SAR) studies indicate that 7-AIQD analogs are dual CB1/CB2 receptor ligands exhibiting high potency with somewhat greater selectivity towards CB2 receptors compared to the previously reported indolequinuclidinone (IQD) analogs. Initial binding assays showed that 7-AIQD analogs 8b , 8d , 8f , 8g and 9b (1 μM) produced more that 50% displacement of the CB1/CB2 non-selective agonist CP-55,940 (0.1 nM). Furthermore, Ki values determined from full competition binding curves showed that analogs 8a , 8b and 8g exhibit high affinity (110, 115 and 23.7 nM, respectively) and moderate selectivity (26.3, 6.1 and 9.2-fold, respectively) for CB2 relative to CB1 receptors. Functional studies examining modulation of G-protein activity demonstrated that 8a acts as a neutral antagonist at CB1 and CB2 receptors, while 8b exhibits inverse agonist activity at these receptors. Analogs 8f and 8g exhibit different intrinsic activities, depending on the receptor examined. Molecular docking and binding free energy calculations for the most active compounds (8a , 8b , 8f , and 8g) were performed to better understand the CB2 receptor-selective mechanism at the atomic level. Compound 8g exhibited the highest predicted binding affinity at both CB1 and CB2 receptors, and all four compounds were shown to have higher predicted binding affinities with the CB2 receptor compared to their corresponding binding affinities with the CB1 receptor. Further structural optimization of 7-AIQD analogs may lead to the identification of potential clinical agents. [ABSTRACT FROM AUTHOR]

Abnormal cannabidiol (abn-CBD) exerts neuroprotective effects in vivo and in vitro. In the present study, we investigated the impact of abn-CBD on the glial production of proinflammatory mediators and scar formation within in vitro models. Primary astrocytic-microglial cocultures and astrocytic cultures from neonatal C57BL/6 mice and CB2 receptor knockout mice were stimulated with lipopolysaccharide (LPS), and the concentrations of tumor necrosis factor α (TNFα), interleukin-6 (IL-6) and nitrite were determined. Furthermore, we performed a live cell microscopy-based scratch-wound assay. After LPS stimulation, TNFα, IL-6 and nitrite production was more strongly increased in cocultures than in isolated astrocytes. Abn-CBD treatment attenuated the LPS-induced production of TNFα and nitrite in cocultures, while IL-6 production remained unaltered. In isolated astrocytes, only LPS-induced TNFα production was reduced by abn-CBD. Similar effects were observed after abn-CBD application in cocultures of CB2 knockout mice. Interestingly, LPS-induced TNFα and nitrite levels were far lower in CB2 knockout cultures compared to wildtypes, while IL-6 levels did not differ. In the scratch-wound assay, treatment with abn-CBD decelerated wound closure when microglial cells were present. Our data shows a differential role of abn-CBD for modulation of glial inflammation and astrocytic scar formation. These findings provide new explanations for mechanisms behind the neuroprotective potential of abn-CBD. [ABSTRACT FROM AUTHOR]