Laura Hernandez-Folgado

Antiobesity effects of the novel in vivo neutral cannabinoid receptor antagonist 5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-3-hexyl-1H-1,2,4-triazole - LH 21

The present study evaluates the pharmacological profile of the new neutral cannabinoid CB1 receptor antagonist 5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-3-hexyl-1H-1,2,4-triazole -LH-21- on feeding behavior and alcohol self-administration in rats, two behaviors inhibited by cannabinoid CB1 receptor antagonists. Administration of LH-21 (0.03, 0.3 and 3 mg/kg) to food-deprived rats resulted in a dose-dependent inhibition of feeding. Subchronic administration of LH-21 reduced food intake and body weight gain in obese Zucker rats. Acute effects on feeding were not associated with anxiety-like behaviors, or induction of complex motor behaviors such as grooming or scratching sequences, usually observed after central administration of cannabinoid receptor blockers with inverse agonist properties. LH-21 did not markedly reduce alcohol self-administration (30% reduction observed only at a high dose of 10 mg/kg). This pharmacological pattern partially overlaps that of the reference cannabinoid CB1 receptor antagonist N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methylpyrazole-3-carboxamide, SR141716A, (0.3, 1 and 3 mg/kg) that reduced feeding and alcohol self-administration with similar efficacy. In vitro analysis of blood-brain barrier permeability using a parallel artificial membrane permeation assay demonstrated that LH-21 has lower permeation through membranes than SR141716A. That was confirmed in vivo by studies showing lower potency of peripherally injected LH-21 when compared to SR141716A to antagonize motor depression induced by intracerebroventricular administration of the CB1 agonist CP55,940. The neutral antagonist profile and the lower penetration into the brain of LH-21 favour this class of antagonists with respect to reference inverse agonists for the treatment of obesity because they potentially will display reduced side effects.

Central versus peripheral antagonism of cannabinoid CB1 receptor in obesity: effects of LH-21, a peripherally acting neutral cannabinoid receptor antagonist, in Zucker rats.

The endogenous cannabinoid system plays an important modulatory role in feeding behaviour and metabolism, acting at both central and peripheral levels. Chronic administration of cannabinoid CB1 receptor antagonists has been found to be effective in experimental obesity. However, clinically available cannabinoid receptor antagonists are inverse agonists that can target CB1 receptors located in both central circuits regulating appetite and motivation and in peripheral organs regulating metabolism and energy expenditure. This profile complicates understanding of cannabinoid CB1 receptor blockade as a therapeutic strategy in obesity and metabolic disorders. This review aims to explore the relevance of both inverse agonism and peripheral cannabinoid receptor blockade on the beneficial actions of chronic cannabinoid receptor blockade, by comparing the actions of the reference antagonist/inverse agonist rimonabant and the newly designed drug LH‐21. LH‐21 is a triazol derivative and a neutral cannabinoid receptor antagonist; it has a poor penetration rate into the central nervous system. When given acutely it decreases food intake and enhances the anorectic actions of oleoylethanolamide, a feeding suppressant lipid that acts on peripheral sensory terminals in a similar way as rimonabant. Unlike rimonabant, chronic administration of LH‐21 (3 mg/kg) reduces feeding but does not improve hypertriglyceridaemia or hypercholesterolaemia; nor does it reduce liver fat deposits in Zucker rats. These results suggest that the inverse agonism and/or the antagonism of central cannabinoid CB1 receptors are necessary for the metabolic benefits of cannabinoid CB1 receptor blockade, but not for the appetite reduction.

Anti‐obesity efficacy of LH‐21, a cannabinoid CB1 receptor antagonist with poor brain penetration, in diet‐induced obese rats

BACKGROUND AND PURPOSE Peripheral blockade of cannabinoid CB1 receptors has been proposed as a safe and effective therapy against obesity, putatively devoid of the adverse psychiatric side effects of centrally acting CB1 receptor antagonists. In this study we analysed the effects of LH‐21, a peripherally acting neutral cannabinoid receptor antagonist with poor brain penetration, in an animal model of diet‐induced obesity.

Chromenopyrazoles: Non‐psychoactive and Selective CB1 Cannabinoid Agonists with Peripheral Antinociceptive Properties

The unwanted psychoactive effects of cannabinoid receptor agonists have limited their development as medicines. These CB1‐mediated side effects are due to the fact that CB1 receptors are largely expressed in the central nervous system (CNS). As it is known that CB1 receptors are also located peripherally, there is growing interest in targeting cannabinoid receptors located outside the brain. A library of chromenopyrazoles designed analogously to the classical cannabinoid cannabinol were synthesized, characterized, and tested for cannabinoid activity. Radioligand binding assays were used to determine their affinities at CB1 and CB2 receptors. Structural features required for CB1/CB2 affinity and selectivity were explored by molecular modeling. Some compounds in the chromenopyrazole series were observed to be selective CB1 ligands. These modeling studies suggest that full CB1 selectivity over CB2 can be explained by the presence of a pyrazole ring in the structure. The functional activities of selected chromenopyrazoles were evaluated in isolated tissues. In vivo behavioral tests were then carried out on the most effective CB1 cannabinoid agonist, 13 a. Chromenopyrazole 13 a did not induce modifications in any of the tested parameters on the mouse cannabinoid tetrad, thus discounting CNS‐mediated effects. This lack of agonistic activity in the CNS suggests that this compound does not readily cross the blood–brain barrier. Moreover, 13 a can induce antinociception in a rat peripheral model of orofacial pain. Taking into account the negative results obtained with the hot‐plate test, the antinociception induced by 13 a in the orofacial test could be mediated through peripheral mechanisms.

Cannabinoid receptor 2 (CB2) agonists and antagonists: a patent update.

ABSTRACT Introduction: Modulation of the CB2 receptor is an interesting approach for pain and inflammation, arthritis, addictions, neuroprotection, and cancer, among other possible therapeutic applications, and is devoid of central side effects. Areas covered: This review highlights the novel scaffolds for CB2 ligands and the diverse therapeutic applications for CB2 modulators disclosed in patents published since 2012. Expert opinion: Structural diversity of CB2 modulator scaffolds characterized the patent literature. Several CB2 agonists reached clinical Phase II for pain management and inflammation. Other therapeutic applications need to be explored such as neuroprotection and/or neurodegeneration.

Allosteric Modulators of the CB1 Cannabinoid Receptor: A Structural Update Review

Abstract In 2005, the first evidence of an allosteric binding site at the CB1R was provided by the identification of three indoles of the company Organon that were allosteric enhancers of agonist binding affinity and, functionally, allosteric inhibitors of agonist activity. Since then, structure–activity relationships of indoles as CB1R modulators have been reported. Targeting the allosteric site on CB1R, new families structurally based on urea and on 3-phenyltropane analogs of cocaine have been discovered as CB1R-negative allosteric modulators (NAMs), respectively, by Prosidion and by the Research Triangle Park. Endogenous allosteric ligands of different nature have been identified more recently. Thus, the therapeutic neuroprotection application of lipoxin A4, an arachidonic acid derivative, as an allosteric enhancer of CB1R activity has been confirmed in vivo. It was also the case of the steroid hormone, pregnenolone, whose negative allosteric effects on Δ9-tetrahydrocannabinol (Δ9-THC) were reproduced in vivo in a behavioral tetrad model and in food intake and memory impairment assays. Curiously, the peroxisome proliferator-activated receptor-γ agonist fenofibrate or polypeptides such as pepcan-12 have been shown to act on the endocannabinoid system through CB1R allosteric modulation. The mechanistic bases of the effects of the phytocannabinoid cannabidiol (CBD) are still not fully explained. However, there is evidence that CBD behaves as an NAM of Δ9-THC- and 2-AG. Allosteric modulation at CB1R offers new opportunities for therapeutic applications. Therefore, further understanding of the chemical features required for allosteric modulation as well as their orthosteric probe dependence may broaden novel approaches for fine-tuning the signaling pathways of the CB1R.

Novel antiobesity agents: Synthesis and pharmacological evaluation of analogues of Rimonabant and of LH21

Searching for novel antiobesity agents, a series of cannabinoid LH21 and of Rimonabant-fatty acid amide analogues have been prepared. Synthesis of pyrazoles 2a-2c was achieved by a two steps simple methodology via α,β-unsaturated ketones. Carboxamides 8a-8h were obtained in good yields from esters 7a-7c by a one-pot procedure which takes place under mild conditions. New compounds have been evaluated in vivo as anorectic agents. Some of them showed interesting properties reducing food intake in rats by a mechanism which does not involve the endocannabinoid system.

Difluorobenzenes revisited: an experimental and theoretical study of spin-spin coupling constants for 1,2-, 1,3-, and 1,4-difluorobenzene

The experimental spin–spin coupling constants (SSCCs) for 1,3‐ and 1,4‐difluorobenzene have been determined anew, and found to be consistent with previously determined values. SSCCs for 1,2‐, 1,3‐, and 1,4‐difluorobenzene have been analyzed by comparing them with the coupling constants computed using the second‐order polarization propagator approximation (SOPPA) and the equation‐of‐motion coupled cluster singles and doubles method (EOM‐CCSD). Eighty experimental values have been analyzed using SOPPA calculations, and a subset of 40 values using both SOPPA and EOM‐CCSD approaches. One‐bond coupling constants 1J(CC) and 1J(CF) are better described by EOM‐CCSD, whereas one‐bond 1J(CH) values are better described by SOPPA. An empirical equation is presented which allows for the prediction of unknown coupling constants from computed SOPPA values. A similar approach may prove useful for predicting coupling constants in larger systems. Copyright

The reaction of NH-indazoles with 1-fluoro-2,4-dinitrobenzene: the unusual formation of benzotriazole-N-oxides

When N-unsubstituted indazoles, like indazole itself, reacted with 1-fluoro-2,4-dinitrobenzene or 1-chloro-2,4,6-trinitrobenzene, three products were obtained whose structures were determined by X-ray diffraction. Besides the two N-substituted nitroaryl derivatives, a third compound was obtained with the same molecular formula (C13H8N4O4) to which was assigned the structure of a derivative of benzotriazole N-oxide. With the combined use of crystallography, NMR and DFT calculations this reaction was studied with special stress on the mechanism of formation of the benzotriazole-N-oxide.

New Methods for the Synthesis of Cannabidiol Derivatives

Cannabidiol (CBD) is one of the most abundant components isolated from Cannabis sativa. However, CBD is a nonpsychotropic phytocannabinoid. In the last decade, there has been a growing interest in its therapeutic effects. This is why this natural product represents a lead structure for the development of new cannabinoid compounds. Even though chemistry of CBD has been explored for more than 30 years, the synthesis of only a few derivatives has been described. This chapter first reviews the synthetic methods for the preparation of CBD and derivatives. Then, it describes procedures for the synthesis of N-heterocyclic derivatives of CBD with, in particular, the preparation and structural characterization of 5-alkyl-2-(1H-pyrazol-3-yl)benzene-1,3-diol.