Synthesis, pharmacological evaluation, and structure-activity relationships studies of sulfur-containing organic derivatives as monoacylglycerol lipase inhibitors

The Monoacylglycerol lipase (MAGL), a lipase hydrolyzing the endocannabinoid 2-arachidonoylglycerol, is considered as a promising target for the treatment of disease states such pain, inflammation and cell proliferation. The aim of the present work is the design, synthesis and establishment of structure-activity relationships of selective and potent monoacylglycerol lipase inhibitors. In the beginning of our study, as the three-dimensional structure of MAGL was not yet elucidated, screening of our own chemical library was performed in order to identify new chemical entities capable of inhibiting MAGL. We have identified the arylthioamide template as privileged scaffold for designing novel monoacylglycerol lipase inhibitors, and have highlighted the role of thiocarbamoyl group in enzyme inhibition. The second part of this work focused on the structure-activity relationships studies performed around disulfiram, in order to increase its activity and selectivity for MAGL inhibition. Indeed, among the incentives to initiate such an endeavour, in addition to containing thiocarbamoyl moiety, like arythioamide derivatives, disulfiram MAGL inhibitory properties have been evidenced in our laboratory. The pharmacomodulations carried out led to the identification of potent and selective disulfide-based MAGL inhibitors. Within the bis(dialkylaminethiocarbonyl)disulfide derivatives series, bis(4-methyl-1-piperazinylthiocarbonyl)disulfide was the most potent and selective MAGL inhibitor. These derivatives irreversibly inhibit MAGL through interaction with Cys208 and Cys242. Finally, as our group reported the MAGL 3D structure (Labar et al., 2010) and we demonstrated that the arylthioamide derivatives, identified as MAGL inhibitors by the screening of our chemical library, could constitute a useful template for designing novel MAGL inhibitors, we have undertaken chemical modifications around this scaffold in order to increase the potency and selectivity for MAGL inhibition as well as to establish the SAR of these new inhibitors. Since potent MAGL inhibitors such as JZL184 as well as triazolopyridine or triazolopyrimidine carboxamides derivatives have been reported to interact optimally with the acyl-binding pocket through a sterically hindered lipophilic moiety, we have developed a series of compounds based on the benzhydrylpiperazine template. The influence of lipophilicity, electronic properties, and conformational behavior was studied; the most potent and selective monoacylglycerol lipase inhibition was observed with 2,4-dinitroaryldithiocarbamate derivatives. These compounds bearing an excellent 2,4-dinitrothiophenolate leaving group irreversibly inhibit MAGL through interaction with the Cys208 or Cys242 and the catalytic Ser122 of MAGL. Among synthesized compounds, [2,4-dinitrophenyl-4-benzhydrylpiperazine-1-carbodithioate] (CK16) and [2,4-dinitrophenyl-4-(4-tert-butylbenzyl) piperazine-1-carbodithioate] (CK37) are the most selective and the potent MAGL inhibitors within this series, respectively. Furthermore, CK37 raises 2-arachidonoylglycerol levels in intact cells. We have demonstrated the MAGL inhibitory properties of sulfur-containing organic derivatives. The efficacy in inhibiting pure MAGL in vitro, coupled to the ability, in case of CK37, to increase cellular levels of 2-AG in intact cells, makes this derivative a promising MAGL inhibitor, which should prove useful for future investigation of endocannabinoid degradation pathways.(FARM 3) -- UCL, 201

Insight into the medicinal chemistry of the endocannabinoid hydrolase inhibitors.

Endocannabinoid hydrolases are nowadays increasingly considered as potential therapeutic targets for treating several pathological states. So far, numerous classes of endocannabinoid hydrolase inhibitors have been described. We herein review the medicinal chemistry of these inhibitors with a particular emphasis on the basis of their design, chemical structure, structure-activity relationships, and inhibition mechanisms

Search for monoglyceride lipase inhibitors : synthesis and screening of arylthioamides derivatives

Monoglyceride lipase (MGL) is the enzyme responsible for the termination of 2-arachidonoylglycerol (2-AG) signalling, an endogenous ligand for the G-protein coupled cannabinoid receptors CB1 and CB2. Its known abundance and physiological roles emphasize the interest of MGL as an attractive therapeutic target. Search for MGL inhibitors was undertaken by screening an arylthioamide series. The evaluation of arylthioamides derivatives activity as MGL inhibitors measured by the hydrolysis of [H-3]-2-oleoylglycerol by human purified MGL led to the identification of (2-chloro-phenyl)-morpholin-4-yl-methanethione (2) and (3-nitro-phenyl) morpholin-4-yl-methanethione (12), which moreover exhibit good selectivity compared with human fatty acid amide hydrolase inhibition

Is cocaine a social drug? Exploration of the stereo-structure of cocaine's pharmacophore

Based on a line of evidence (logP, pKa, 1H-, and 13C-NMR, and molecular modeling studies), it appears that cocaine undergoes a hydrophobic collapse which may account for its unprecedented ADME properties, in particular, its exceptional capacity to cross biological membranes. Using molecular simulation techniques, the hypothesis of hydrophobic collapse undergone by the protonated form of cocaine was substantiated using semi-empirical quantum calculations (mainly AM1 and PM3) performed as well as ab initio quantum calculations (6-31 G**). A molecular electrostatic potential map of the internally hydrogen-bonded structure was acquired under AM1 and showed a continuum of high electron density in the central part of the molecule around the methyl ammonium and the two ester moieties. This picture is consistent with the picture of the ammonium being locked between the two C=O and forming a strong canonical primary H bond with the methyl ester and a weaker secondary H bond (non-canonical) with the benzoate ester. Cocaine represents the prototypical example of molecular concision because the pharmacophore and the vector are embedded in the same molecular scaffold. © 2012 Springer Science+Business Media, LLC

Synthesis and pharmacological evaluation of antioxidant chalcone derivatives of 2(3H)-benzoxazolones

Chalcones featuring an analgesic/anti-inflammatory pharmacophore, i.e., the 2(3H)-benzoxazolone heterocycle, on the one hand, and a radical scavenger moiety, i.e., 2,6-di-t-butylphenol, on the other hand were synthesized by condensation of a ketone 2(3H)-benzoxazolone precursor with 3,5-di-t-butyl-4-hydroxybenzaldehyde. Among the various methods explored (acid homogenous or heterogenous catalysis, base catalysis), heterogenous catalysis conditions using KSF Montmorillonite were found to be the most convenient. The E-geometry of the so-obtained chalcones was ascertained both by H-1 and C-13-nuclear magnetic resonance (NMR) spectroscopy as well as B3LYP/6-31G(**) quantum mechanics calculations. Chalcones 1-8 were pharmacologically evaluated in vitro for their ability to prevent human low-density lipoprotein (LDL) copper-induced oxidation using Cu2+ as oxidizing agent. Compound 4 emerged as the most promising agent as it was able to inhibit copper-mediated human LDL oxidation with an activity ten times greater than that of Probucol, a reference antioxidant drug

Design and synthesis of 3-acyl-2(3H)-benzoxazolone and 3-acyl-2(3H)-benzothiazolone derivatives

A simpler and efficient “green” method using solid sodium hydroxide in a solvent mixture of acetone/water was found to catalyze N-acylation of 2(3H)-benzoxazolones and 2(3H)-benzothiazolones for facile and rapid synthesis of N-acyl derivatives in excellent yields. This method was applied to the synthesis of a series of 132 compounds employing a variety of acyl chlorides

PET imaging of fatty acid amide hydrolase in the brain : synthesis and biological evaluation of an C-11-labelled URB597 analogue

Introduction: Fatty acid amide hydrolase (FAAH) is part of the endocannabinoid system (ECS) and has been linked to the aetiology of several neurological and neuropsychiatric disorders. So far no useful PET or SPECT tracer for in vivo visualisation of FAAH has been reported. We synthesized and evaluated a carbon-11-labeled URB597 analogue, biphenyl-3-yl [C-11]-4-methoxyphenylcarbamate or [C-11]-1, as potential FAAH imaging agent. Methods: The inhibitory activity of 1 was determined in vitro using recombinant FAAH. Radiosynthesis of [(CH)-C-11]-1 was performed by methylation using [C-11]-CH3I, followed by HPLC purification. Biological evaluation was done by biodistribution studies in wild-type and FAAH knock-out mice, and by ex vivo and in vivo metabolite analysis. The influence of URB597 pretreatment on the metabolisation profile was assessed. Results: [C-11]-1 was obtained in good yields and high radiochemical purity. Biodistribution studies revealed high brain uptake in wild-type and FAAH knock-out mice, but no retention of radioactivity could be demonstrated. Metabolite analysis and URB597 pretreatment confirmed the non-FAAH-mediated metabolisation of [C-11]-1. The inhibition mechanism was determined to be reversible. In addition, the inhibition of URB597 appeared slowly reversible. Conclusions: Although [C-11]-1 inhibits FAAH in vitro and displays high brain uptake, the inhibition mechanism seems to deviate from the proposed carbamylation mechanism. Consequently, it does not covalently bind to FAAH and will not be useful for mapping the enzyme in vivo. However, it represents a potential starting point for the development of in vivo FAAH imaging tools. (C) 2010 Published by Elsevier Inc

Synthesis, caracterization, trypanosomal activities on Trypanosoma bruceibrucei and toxicity against Artemiasalina leach of N(4)-aryl semicarbazones and thiosemicarbazones

N(4)-phenyl substituted semicarbazones and thiosemicarbazones (1-4) of propiophenone and 4'- methylacetophenone have been synthesized and characterized by spectrometrical methods analyses (IR, RMN 1H & 13C, SM). All compounds were evaluated for their in vitro trypanosomal activity against the bloodstream form of the strain 427 of Trypanosomabruceibrucei and have been tested on larvaeofbrine shrimp, Artemiasalina LEACH, for their toxic activity. The selectivity index (SI) of each molecule was too designed. In the group, propiophenone 4- phenyl-3-thiosemicarbazone 4 has exhibited greater trypanocidal activity with a half-inhibitory concentration (IC 50) value equal to 7.63 micromolar (μM). 4'-methylacetophenone 4-phenylsemicarbazone 1 showed moderate antitrypanosomal activity (IC 50 = 62.54 μM). Other, 2 and 3, presented little or no activity against the parasite (IC 50> 100 μM). Except propiophenone 4-phenylsemicarbazone 2 which offered a toxic activity on larvae given the halflethal concentration LC 50 = 107.49 μM and SI = 0.518 281 μM and SI > 1, compounds 1, 3 and 4). They turn out quite selective on the parasite. Synthesized compounds could constitute a new class of anti-trypanosomal drug candidates

Synthesis, characterization, anti-trypanosomal activity and toxicity against Artemia salina Leach of thiobenzamides and derivatives

This work aims to synthesize, characterize of thioamides benzaldehyde and 4-(dimethylamino)benzaldehyde and assess their in votrotrypanocidal activity and totoxicity. The Willgerodt-Kindler reaction preferred for the synthesis of thioamides morpholin-4-yl (phenyl) methanethione 1 and [4-(dimethylamino) phenyl]-(morpholin-4-yl) methanethione 2, is catalyzed with montmorillonite K-10 and in a microwave oven. The structures of the thioamides were characterized and confirmed by IR spectrometry, nuclear magnetic resonance (1H and 13C NMR) and mass spectrometry (MS) Their trypanocidal activity was evaluated in the blood stream form of the strain of Trypanosoma brucei brucei 427 using the "Lilit, Alamar Blue" (Baltz et al., 1985; Hirumi et al., 1994; Räz et al., 1997) and cytotoxicity on brine shrimp larvae (Artemia salina Leach) using the method of Michael et al. (1956) resumed by Vanhaecke et al. (1981) and Sleet and Brendel (1983). The compounds1 (IC50> 483.09 μM) and 2 (IC50> 400 μM) have weak trypanocidal activities. However the larvae were sensitive to 2 (LD50 = 214 ± 9 μM) and therefore it could be used in cancer treatment

Synthesis, characterization and anti-trypanosomal activity of R-(-)carvone and arylketones-thiosemi carbazones and toxicity against Artemia salina Leach

This work is focused on the synthesis and characterization of a series of N(4)- substituted thiosemicarbazones and the evaluation of their in-vitro anti-trypanosomal activity and toxicity. A series of thiosemicarbazones (1-4) and N(4)-phenyl-3-thiosemicarbazones (5-8) have been synthesized on R-(-)carvone, acetophenone, 4’-methylacetophenone and benzophenone by condensation reaction with good yields. All compounds were characterized by spectrometrical analysis methods infrared IR, nuclear magnetic resonance NMR (1H &13C) and mass spectrometry MS, confirming their structures respectively, and were evaluated for their invitro parasitic activity against the bloodstream form of the strain 427 of Trypanosoma brucei brucei using the “LILIT, Alamar Blue” method (Baltzet al., 1985; Hirumi et al., 1994; Räz et al.,1997). Their toxicity against brine shrimp larvae (Artemia salina Leach) was studied, according to the method of Michael et al. (1956) resumed byVanhaecke et al. (1981) and bySleet and Brendel (1983). Some of them have exhibited a strong trypanocidal activity, especially compounds 8, 3, 1 and 4 with their half-inhibitory concentrations (IC50) values equal to 8.48, 8.73, 39.71 and 67.17 micro-molar (µM) respectively. Except compounds 1 and 4whose half-lethal concentration (LC50) values were20.58 and 33.72 µM respectively and then toxics, all synthesized compounds showed negligible toxicity against Artemia salinaL. (LC50> 280 µM) and good selectivity (S) (SI “index” =1)