Activity of pyridyl-pyrazolone derivatives against Trypanosoma cruzi.

New affordable drugs are needed for the treatment of infection with the protozoan parasite Trypanosoma cruzi responsible for the Chagas disease (CD). Only two old drugs are currently available, nifurtimox and benznidazole (Bz) but they exhibit unwanted side effects and display a weak activity in the late chronic phase of the disease. In this context, we evaluated the activity of a series of aryl-pyrazolone derivatives against T cruzi, using both bloodstream trypomastigote and intracellular amastigote forms of the parasite. The test compounds originate from a series of anticancer agents targeting the immune checkpoint ligand PD-L1 and bear an analogy with known anti-trypanosomal pyrazolones. A first group of 6 phenyl-pyrazolones was tested, revealing the activity of a single pyridyl-pyrazolone derivative. Then a second group of 8 compounds with a common pyridyl-pyrazolone core was evaluated. The in vitro testing process led to the identification of two non-cytotoxic and highly potent molecules against the intracellular form of T. cruzi, with an activity comparable to Bz. Moreover, one compound revealed an activity largely superior to that of Bz against bloodstream trypomastigotes, while being non-cytotoxic (selectivity index >1000). Unfortunately, the compound showed little activity in vivo, most likely due to its very limited plasma stability. However, the study opens novel perspectives for the design of new anti-trypanosomal products and the mechanism of action of the compounds is discussed.

Novel PD-L1-Targeted Phenyl-Pyrazolone Derivatives with Antioxidant Properties.

Orally-active anticancer small molecules targeting the PD-1/PD-L1 immune checkpoint are actively searched. Phenyl-pyrazolone derivatives with a high affinity for PD-L1 have been designed and characterized. In addition, the phenyl-pyrazolone unit acts as a scavenger of oxygen free radicals, providing antioxidant effects. The mechanism is known for the drug edaravone (1) which is also an aldehyde-reactive molecule. The present study reports the synthesis and functional characterization of new molecules (2-5) with an improved anti-PD-L1 activity. The leading fluorinated molecule 5 emerges as a potent checkpoint inhibitor, avidly binding to PD-L1, inducing its dimerization, blocking PD-1/PD-L1 signaling mediated by phosphatase SHP-2 and reactivating the proliferation of CTLL-2 cells in the presence of PD-L1. In parallel, the compound maintains a significant antioxidant activity, characterized using electron paramagnetic resonance (EPR)-based free radical scavenging assays with the probes DPPH and DMPO. The aldehyde reactivity of the molecules was investigated using 4-hydroxynonenal (4-HNE), which is a major lipid peroxidation product. The formation of drug-HNE adducts, monitored by high resolution mass spectrometry (HRMS), was clearly identified and compared for each compound. The study leads to the selection of compound 5 and the dichlorophenyl-pyrazolone unit as a scaffold for the design of small molecule PD-L1 inhibitors endowed with antioxidant properties.

Antioxidant Properties and Aldehyde Reactivity of PD-L1 Targeted Aryl-Pyrazolone Anticancer Agents.

Small molecules targeting the PD-1/PD-L1 checkpoint are actively searched to complement the anticancer arsenal. Different molecular scaffolds have been reported, including phenyl-pyrazolone derivatives which potently inhibit binding of PD-L1 to PD-1. These molecules are structurally close to antioxidant drug edaravone (EDA) used to treat amyotrophic lateral sclerosis. For this reason, we investigated the capacity of five PD-L1-binding phenyl-pyrazolone compounds (1-5) to scavenge the formation of oxygen free radicals using electron spin resonance spectroscopy with DPPH/DMPO probes. In addition, the reactivity of the compounds toward the oxidized base 5-formyluracil (5fU) was assessed using chromatography coupled to mass spectrometry and photodiode array detectors. The data revealed that the phenyl-pyrazolone derivatives display antioxidant properties and exhibit a variable reactivity toward 5fU. Compound 2 with a N-dichlorophenyl-pyrazolone moiety cumulates the three properties, being a potent PD-L1 binder, a robust antioxidant and an aldehyde-reactive compound. On the opposite, the adamantane derivative 5 is a potent PD-L1 binding with a reduced antioxidant potential and no aldehyde reactivity. The nature of the substituent on the phenyl-pyrazolone core modulates the antioxidant capacity and reactivity toward aromatic aldehydes. The molecular signature of the compound can be adapted at will, to confer additional properties to these PD-L1 binders.

One- or Two-Step Synthesis of C-8 and N-9 Substituted Purines.

A novel and original strategy to obtain rapidly a large diversity of C-8 and N-9 substituted purines was developed. The present procedure describes annulation reactions in one or two steps starting from 5-aminoimidazole-4-carbonitriles 1-8 in moderate to good yields. 8,9-Disubstituted-6,9-dihydro-1H-purin-6-ones 9-14, 6-amino-8,9-disubstituted-3,9-dihydro-2H-purin-2-ones 15-20, 8,9-disubstituted-3,9-dihydro-2H-purin-2,6-diamines 21-24 and 6-imino-1-phenyl-8,9-disubstituted-6,9-dihydro-1H-purin-2-(3H)-ones 25-26 were synthesized in one step using formic acid, urea, guanidine carbonate, and phenylisocyanate, respectively, whereas 8,9-disubstituted-9H-purin-6-amines 27-31 and 6-imino-8,9-disubstituted-6,9-dihydro-1H-purin-1-amines 32-33 were obtained in two steps using formamide and hydrazine, respectively.

Design, synthesis and biological evaluation of potent FAAH inhibitors.

A new series of 3-carboxamido-5-aryl-isoxazoles was designed, synthesized and evaluated for their biological activity. Different pharmacomodulations have been explored and the lipophilicity of these compounds was assessed. Investigation of the in vitro biological activity led to the identification of 5 compounds as potent FAAH inhibitors, their good FAAH inhibition capacity is probably correlated with their suitable lipophilicity. Specifically, compound 25 showed similar inhibition potency against FAAH in comparison with URB597, one of the most potent FAAH inhibitor known to date.

Antagonists of the P2X7 receptor: mechanism of enantioselective recognition using highly sulfated and sulfobutylether cyclodextrins by capillary electrokinetic chromatography.

This work concerns the successful enantiomeric separation of pyroglutamic acid derivatives, known to be P2X7 receptor antagonists, achieved by electrokinetic chromatography. After a broad screening, two negatively charged cyclodextrins, sulfobutylether-ß-cyclodextrin (SBE-ß-CD), and highly sulfated-γ-cyclodextrin (HS-γ-CD) were chosen as stereoselective agents to cooperate with the BGE for complexation. A fused silica capillary coated with polyethylene oxide, filled with a phosphate buffer (25 mM, pH 2.5) containing various concentrations of CD, was used. Assuming a 1:1 stoichiometry, calculations of the binding constants, employing the three different linearization plots, were performed from the corrected electrophoretic mobilities values of the enantiomers, at different concentrations of SBE-ß-CD and HS-γ-CD in the BGE. The highest complexation was found with the SBE-ß-CD. Among the three equations, results showed better linearity (R(2) > 0.99) using the y-reciprocal fit. This plotting method was then performed to determine the binding constants of each enantiomer at different temperature for compounds 1 and 2 with SBE-ß-CD and HS-γ-CD in order to access to the thermodynamic parameters of the eight complexes. The linearity of the Van't Hoff plot, in the range of 288-303 K leading to negative enthalpy values, showed that the complexation phenomenon is enthalpically controlled and thermodynamically favored.

Switching cannabinoid response from CB(2) agonists to FAAH inhibitors.

A series of 3-carboxamido-5-aryl-isoxazoles designed as CB2 agonists were evaluated as FAAH inhibitors. The pharmacological results led to identify structure-activity relationships enabling to switch cannabinoid response from CB2 agonists to FAAH inhibitors. Two compounds were selected for their FAAH and/or CB2 activity, and evaluated in a colitis model for their anti-inflammatory activity. Results showed that compounds 10 and 11 inhibit the development of DSS-induced acute colitis in mice and then, are interesting leads to explore new drug candidates for IBD.

3-Carboxamido-5-aryl-isoxazoles as new CB2 agonists for the treatment of colitis.

Recent investigations showed that anandamide, the main endogenous ligand of CB1 and CB2 cannabinoid receptors, possesses analgesic, antidepressant and anti-inflammatory effects. In the perspective to treat inflammatory bowel disease (IBD), our approach was to develop new selective CB2 receptor agonists without psychotropic side effects associated to CB1 receptors. In this purpose, a new series of 3-carboxamido-5-aryl-isoxazoles, never described previously as CB2 receptor agonists, was designed, synthesized and evaluated for their biological activity. The pharmacological results have identified great selective CB2 agonists with in vivo anti-inflammatory activity in a DSS-induced acute colitis mouse model.

[From cannabis to selective CB2R agonists: molecules with numerous therapeutical virtues]. / Du cannabis aux agonistes sélectifs du récepteur CB2 - des molécules aux nombreuses vertus thérapeutiques.

Originally used in Asia for the treatment of pain, spasms, nausea and insomnia, marijuana is the most consumed psychotropic drug worldwide. The interest of medical cannabis has been reconsidered recently, leading to many scientific researches and commercialization of these drugs. Natural and synthetic cannabinoids display beneficial antiemetic, anti-inflammatory and analgesic effects in numerous diseases, however accompanied with undesirable effects due to the CB1 receptor. Present researches focus on the design of therapeutical molecules targeting the CB2 receptors, and thus avoiding central side effects and therefore psychotropic effects caused by the CB1 receptor.

Receptor Interacting Ser/Thr-Protein Kinase 2 as a New Therapeutic Target.

Receptor interacting serine/threonine protein kinase 2 (RIPK2) is a downstream signaling molecule essential for the activation of several innate immune receptors, including the NOD-like receptors (NOD1 and NOD2). Recognition of pathogen-associated molecular pattern proteins by NOD1/2 leads to their interaction with RIPK2, which induces release of pro-inflammatory cytokines through the activation of NF-κB and MAPK pathways, among others. Thus, RIPK2 has emerged as a key mediator of intracellular signal transduction and represents a new potential therapeutic target for the treatment of various conditions, including inflammatory diseases and cancer. In this Perspective, first, an overview of the mechanisms that underlie RIPK2 function will be presented along with its role in several diseases. Then, the existing inhibitors that target RIPK2 and different therapeutic strategies will be reviewed, followed by a discussion on current challenges and outlook.

Pyrazolones as inhibitors of immune checkpoint blocking the PD-1/PD-L1 interaction.

Immuno-therapy has become a leading strategy to fight cancer. Over the past few years, immuno-therapies using checkpoint inhibitor monoclonal antibodies (mAbs) against programmed death receptor 1 (PD-1) and programmed death ligand 1 (PD-L1) have demonstrated improved survival compared with chemotherapy. We describe the microwave-assisted synthesis and the characterization of an innovative series of synthetic compounds endowed with nanomolar activity against PD-L1. The properties of the compounds were characterized using several biophysical techniques including microscale thermophoresis (MST) and fluorescence resonance energy transfer (FRET) measurements. A few small molecules demonstrated a high affinity for human PD-L1, potently disrupted the PD-L1:PD-1 interaction and inhibited Src homology region 2 domain-containing phosphatase (SHP2) recruitment to PD-1. More than 30 molecules from the pyrazolone family have been synthesized and 5 highly potent "PD-L1 silencing compounds" have been identified, based on in vitro measurements. Structure-activity relationships have been defined and ADME properties were evaluated. The phenyl-pyrazolone unit offers novel perspectives to design PD-L1-targeting agents, potentially useful to combat cancer and other pathologies implicating the PD-1/PD-L1 checkpoint.

New FAAH inhibitors based on 3-carboxamido-5-aryl-isoxazole scaffold that protect against experimental colitis.

Growing evidence suggests a role for the endocannabinoid (EC) system, in intestinal inflammation and compounds inhibiting anandamide degradation offer a promising therapeutic option for the treatment of inflammatory bowel diseases. In this paper, we report the first series of carboxamides derivatives possessing FAAH inhibitory activities. Among them, compound 39 displayed significant inhibitory FAAH activity (IC(50)=0.088 µM) and reduced colitis induced by intrarectal administration of TNBS.

A small-molecule P2RX7 activator promotes anti-tumor immune responses and sensitizes lung tumor to immunotherapy.

Only a subpopulation of non-small cell lung cancer (NSCLC) patients responds to immunotherapies, highlighting the urgent need to develop therapeutic strategies to improve patient outcome. We develop a chemical positive modulator (HEI3090) of the purinergic P2RX7 receptor that potentiates αPD-1 treatment to effectively control the growth of lung tumors in transplantable and oncogene-induced mouse models and triggers long lasting antitumor immune responses. Mechanistically, the molecule stimulates dendritic P2RX7-expressing cells to generate IL-18 which leads to the production of IFN-γ by Natural Killer and CD4+ T cells within tumors. Combined with immune checkpoint inhibitor, the molecule induces a complete tumor regression in 80% of LLC tumor-bearing mice. Cured mice are also protected against tumor re-challenge due to a CD8-dependent protective response. Hence, combination treatment of small-molecule P2RX7 activator followed by immune checkpoint inhibitor represents a strategy that may be active against NSCLC.

Synthesis and biological activity of N-aroyl-tetrahydro-gamma-carbolines.

Research on dual inhibitors of both 5-LOX and COXs gained interest due to the overexpressions of these enzymes during the malignant state of the evolution of prostate cancer. In order to take part in this research, new N-aroyl-tetrahydro-gamma-carbolines issued from the modification of Indomethacin have been synthesised. As for the NSAIDs, the compounds have been tested for their activity against COX(1), COX(2) plus against 5-LOX and against the proliferation of malignant prostate cancer. Interesting cytotoxic activities and selectivities of some tetrahydro-gamma-carboline derivatives have been obtained.

Pyroglutamide-Based P2X7 Receptor Antagonists Targeting Inflammatory Bowel Disease.

This report deals with the design, the synthesis, and the pharmacological evaluation of pyroglutamide-based P2X7 antagonists. A dozen were shown to possess improved properties, among which inhibition of YO-PRO-1/TO-PRO-3 uptake and IL1ß release upon BzATP activation of the receptor and dampening signs of DSS-induced colitis on mice, in comparison with reference antagonist GSK1370319A. Docking study and biological evaluation of synthesized compounds has highlighted new SAR, and low toxicity profiles of pyroglutamides herein described are clues for the finding of a usable h-P2X7 antagonist drug. Such a drug would raise the hope for a cure to many P2X7-dependent pathologies, including inflammatory, neurological, and immune diseases.

Benzo[d]thiazol-2(3H)-ones as new potent selective CB2 agonists with anti-inflammatory properties.

The high distribution of CB2 receptors in immune cells suggests their important role in the control of inflammation. Growing evidence offers this receptor as an attractive therapeutic target: selective CB2 agonists are able to modulate inflammation without triggering psychotropic effects. In this work, we report a new series of selective CB2 agonists based on a benzo[d]thiazol-2(3H)-one scaffold. This drug design project led to the discovery of compound 9, as a very potent CB2 agonist (Ki = 13.5 nM) with a good selectivity versus CB1. This compound showed no cytotoxicity, acceptable ADME-Tox parameters and demonstrates the ability to counteract colon inflammatory process in vivo.

Development of novel oxazolo[5,4-d]pyrimidines as competitive CB2 neutral antagonists based on scaffold hopping.

A series of novel oxazolo[5,4-d]pyrimidines was designed via a scaffold hopping strategy and synthesized through a newly developed approach. All these compounds were evaluated for their biological activity toward CB1/CB2 cannabinoid receptors, their metabolic stability in mice liver microsomes and their cytotoxicity against several cell lines. Eight compounds have been identified as CB2 ligands with Ki values less than 1 µM. It is noteworthy that 2-(2-chlorophenyl)-5-methyl-7-(4-methylpiperazin-1-yl) oxazolo[5,4-d]pyrimidine 47 and 2-(2-chlorophenyl)-7-(4-ethylpiperazin-1-yl)- 5-methyloxazolo[5,4-d]pyrimidine 48 showed CB2 binding affinity in the nanomolar range and significant selectivity over CB1 receptors. Interestingly, functionality studies imply that they behave as competitive neutral antagonists. Moreover, all tested compounds are devoid of cytotoxicity toward several cell lines, including Chinese hamster ovary cells (CHO) and human colorectal adenocarcinoma cells HT29.

Synthesis and biological evaluation of ferrocene-based cannabinoid receptor 2 ligands.

Ferrocene analogs of known fatty acid amide hydrolase inhibitors and CB2 ligands have been synthesized and characterized spectroscopically and crystallographically. The resulting bio-organometallic isoxazoles were assayed for their effects on CB1 and CB2 receptors as well as on fatty acid amide hydrolase. None had any fatty acid amide hydrolase activity but compound 3, 5-(2-(pentyloxy)phenyl)-N-ferrocenylisoxazole-3-carboxamide, was found to be a potent CB2 ligand (Ki = 32.5 nM).

Pharmacomodulations around the 4-oxo-1,4-dihydroquinoline-3-carboxamides, a class of potent CB2-selective cannabinoid receptor ligands: consequences in receptor affinity and functionality.

CB2 receptor selective ligands are becoming increasingly attractive drugs due to the potential role of this receptor in several physiopathological processes. Thus, the development of our previously described series of 4-oxo-1,4-dihydroquinoline-3-carboxamides was pursued with the aim to further characterize the structure-affinity and structure-functionality relationships of these derivatives. The influence of the side chain was investigated by synthesizing compounds bearing various carboxamido and keto substituents. On the other hand, the role of the quinoline central scaffold was studied by synthesizing several 6-, 7-, or 8-chloro-4-oxo-1,4-dihydroquinolines, as well as 4-oxo-1,4-dihydronaphthyridine and 4-oxo-1,4-dihydrocinnoline derivatives. The effect of these modifications on the affinity and functionality at the CB2 receptor was studied and allowed for the characterization of new selective CB2 receptor ligands.

Small scale separation of isoxazole structurally related analogues by chiral supercritical fluid chromatography.

Chromatographic preparative enantioseparation is now the preferred method to obtain milligram amounts of pure enantiomers in the first step of the development of a therapeutic molecule. Supercritical fluid chromatography has many advantages over liquid chromatography and was therefore chosen for the small scale enantioseparation of four original 3-carboxamido-5-aryl isoxazole molecules, ligands of the CB2 cannabinoid receptors. The preparation of about 10mg of each of the eight enantiomers was achieved successfully on a Chiralpak® AD-H (tris-3,5-dimethylphenylcarbamate of amylose) polysaccharide based stationary phase with various percentages of ethanol as a co-solvent, through mixed-stream injections and touching-band approach. For the all compounds, no peak distortion is observed during the volume overloading, in spite of the injection mode. Production rate (mgmin-1), productivity (kilogram of racemate separated per kilogram of CSP per day (kkd)) and solvent usage were found higher and environmental factors (E Factor) were found lower for compounds 1 and 3. The yields of each purified enantiomer were comprised between 60 and 94%. In order to improve the limit of detection calculated with the diode array detector, the hyphenation with an evaporating light scattering detector was explored and a factor of ten was won. Lastely, the enantiomeric excess and achiral purity of each of the eight individual enantiomer generated was determined and found higher than 98%.