Evaluation of various polysaccharide-based stationary phases for enantioseparation of chloro-containing derivatives in normal phase liquid chromatography.

Six polysaccharide-based chiral stationary phases were screened to separate the enantiomers of six chloro-containing derivatives and one derivative bearing electron donating mesomeric substituents, chosen for comparison. These compounds are expected to be P2X7 receptor antagonists with potential anti-inflammatory activity. The study was carried out with four different mobile phases composed of n-heptane and ethanol or isopropanol. Thus, a total of 168 experiments were implemented to find the best conditions aimed at scaling-up the separation of these anti-inflammatory compounds. Chiralpak AD-H separated half of them, i.e., 1, 2, and 6; Chiralpak AS separated also three out of the six compounds, i.e., 1, 2, and 3; Lux Cellulose-5 separated 2, 4, and 6; Lux Cellulose-2 separated 1, 2, and 4; Chiralcel OD-H separated compounds 2 and 5; and finally Chiralcel OJ separated only 3, thus having the lowest rate of success. Additionally, the influence of (i) the stationary and mobile phases and (ii) the chemical structure of the analytes on retention and resolution was investigated.

Ultrasound-Assisted Synthesis of Pyrazoline Derivatives as Potential Antagonists of RAGE-Mediated Pathologies: Insights from SAR Studies and Biological Evaluations.

In the context of age-related disorders, the receptor of advanced glycation end products (RAGE), plays a pivotal role in the pathogenesis of these conditions by triggering downstream signaling pathways associated with chronic inflammation and oxidative stress. Targeting this inflammaging phenomenon with RAGE antagonists holds promise for interventions with broad implications in healthy aging and the management of age-related conditions. This study explores the structure-activity relationship (SAR) of pyrazoline-based RAGE antagonists synthesized using an ultrasound-assisted green one-pot two-steps methodology. Our investigation identifies phenylurenyl-pyrazoline 2g as a promising candidate, demonstrating superior efficiency compared to the reference antagonist Azeliragon (IC50 = 13 µM). Compound 2g exhibits potent inhibition of the AGE2-BSA/sRAGE interaction (IC50 = 22 µM) and favorable affinity in Microscale Thermophoresis (MST) assays (Kd = 17.1 µM), along with a favorable safety profile, with no apparent cytotoxicity observed in vitro in the MTS assay. These findings underscore the potential of pyrazoline-derived RAGE antagonists as therapeutic agents for addressing age-related disorders.

Development of Receptor for Advanced Glycation End Products (RAGE) ligands through target directed dynamic combinatorial chemistry: a novel class of possible antagonists.

RAGE is a transmembrane receptor of immunoglobulin family that can bind various endogenous and exogenous ligands, initiating the inflammatory downstream signaling pathways, including inflammaging. Therefore, RAGE represents an attractive drug target for age-related diseases. For the development of small-molecule RAGE antagonists, we employed protein-templated dynamic combinatorial chemistry (ptDCC) using RAGE's VC1 domain as a template, the first application of this approach in the context of RAGE. The affinities of DCC hits were validated using microscale thermophoresis. Subsequent screening against AGE2 (glyceraldehyde-modified AGE)-sRAGE (solubleRAGE) (AGE2-BSA/sRAGE) interaction using ELISA tests led to the identification of antagonists with micromolar potency. Our findings not only demonstrate the successful application of ptDCC on RAGE but also highlight its potential to address the pressing need for alternative strategies for the development of small-molecule RAGE antagonists, an area of research that has experienced a slowdown in recent years.

Capillary electrokinetic chromatography for chiral separation of potential SARS-CoV-2 3CL protease inhibitors.

In this work, a capillary electrophoresis method was developed as a quality control tool to determine the enantiomeric purity of a series of five chiral compounds evaluated as potential severe acute respiratory syndrome coronavirus 2 3CL protease inhibitors. The first cyclodextrin tested, that is, highly sulfated-ß-cyclodextrin, at 6% (m/v) in a 25 mM phosphate buffer, using a capillary dynamically coated with polyethylene oxide, at an applied voltage of 15 kV and a temperature of 25°C, was found to successfully separate the five derivatives. The limits of detection and quantification were calculated together with the greenness score of the method in order to evaluate the method in terms of analytical and environmental performance. In addition, it is noteworthy that simultaneously high-performance liquid chromatography separation of the enantiomers of the same compounds with two different columns, the amylose tris(3,5-dimethylphenylcarbamate)-coated and the cellulose tris(3,5-dichlorophenylcarbamate)-immobilized on silica stationary phases, was studied. Neither the former stationary phase nor the latter was able to separate all derivatives in a mobile phase consisting of n-heptane/propan-2-ol 80/20 (v/v).

Evaluation of greenness and analytical performances of separative methods for chiral separation of novel lactam-based P2RX7-antagonists.

In this work, a preparative supercritical fluid chromatography (SFC) method was first developed to separate a series of chiral compounds evaluated as lactam-based P2RX7 antagonists. Subsequently, high-performance liquid chromatography, SFC, and capillary electrophoresis (CE) were comparatively investigated as QC tools to determine the enantiomeric purity of the separated isomers, including analytical performance and greenness. The screening of the best conditions was carried out in liquid and SFC on the nine derivatives and the amylose tris(3,5-dimethylphenylcarbamate)-based chiral stationary phase was found to be highly efficient. The same screening was carried out in CE and very different conditions, either in acidic or basic background electrolyte and different cyclodextrins used as chiral selectors, allowed the separation of six of the nine derivatives. 1-((3,4-Dichlorophenyl)carbamoyl)-5-oxopyrrolidine-2-carboxylic acid (compound 1) was chosen as a probe, and its semi-preparative separation by SFC and enantiomeric verification using the three techniques are presented. Its limit of detection and limit of quantification are calculated for each method. Finally, the greenness of each quality control method was evaluated.

Separation of planar chiral ferrocenes by capillary electrokinetic chromatography and liquid chromatography.

Capillary electrokinetic chromatography (CEKC) and liquid chromatography (LC) methods were explored for the enantiomeric separation of six unsymmetrically disubstituted ferrocene derivatives. In normal-phase mode liquid chromatography, the use of n-heptane, ethanol or isopropanol with 1% n-butylamine as mobile phase on six polysaccharide-based columns, allowed to fully separate the enantiomers of three compounds out of the six (i.e 7-chloro-N-(2-((dimethylamino)methyl)ferrocenyl)quinolin-4-amine (ferroquine) (compound 1), 1-[(1S)-(1-Aminoethyl)]-2-(diphenylphosphino)ferrocene (compound 5) and 1-[(1R)-1-(Dicyclohexylphosphino)ethyl]-2-(diphenylphosphino)ferrocene (compound 6). Among the columns used, the Lux i-Cellulose-5 was the most effective. In capillary electrokinetic chromatography, a phosphate buffer of 25 mM concentration and pH equal to 2.5 was chosen as background electrolyte, leading to cationic ferrocene derivatives. The addition of neutral cyclodextrins was undertaken first and native ß- or γ-cyclodextrins were found to resolve the enantiomers of two derivatives. Then, 15 mM of anionic cyclodextrins were added to the background electrolyte. The use of SBE-ß-CD, S-ß-CD or S-γ-CD have allowed the separation of the enantiomers for most of the ferrocene derivatives studied with high resolution values in short migration time. For instance, for 1-(R)-2-(Diphenylphosphino)ethyldi-tert-butylphosphine ferrocene (compound 2), the migration times were less than 2 minutes and the resolution value was equal to 3.52 in short-end mode with 15 mM S-ß-CD, at 25 kV and 25°C. Finally, a dual cyclodextrins system was tested using 15 mM of S-ß-CD plus 15 mM HP-γ-CD in the phosphate buffer. This system allowed the improved separation of two ferrocene derivatives with an unusual resolution value equal to 41.5 in long-end mode. Overall, CEKC showed better enantioseparating power of the six chiral ferrocenes studied than liquid chromatography.

Supercritical fluid chromatography for separation of chiral planar metallocenes.

Unsymmetrically disubstituted metallocene derivatives, characterized as the first sandwich structure, have found interest in asymmetrical synthesis and in medicinal chemistry as well. Besides, they present a particular case of chirality. Twenty original and six commercially available molecules presenting either i) a planar chirality or ii) an asymmetrical carbon containing group or iii) being symmetrically substituted were analyzed in supercritical fluid chromatography on eleven polysaccharide-based chiral stationary phases with carbon dioxide containing 30% of methanol or 2-propanol as a co-solvent mobile phase. A basic additive, either diethylamine, triethylamine or n-butylamine was also required at 1% to the co-solvent for elution. While some of the tested chiral stationary phases provided enantioseparation for the racemates, chlorinated cellulosic phases proved to be both highly retentive and highly enantioselective towards these particular species with the highest rate of success compared to their non-chlorinated counterparts. For instance, the resolution value was equal to 14.1 for one ferrocene derivative in one-hour analysis time on cellulose tris(3,5-dichlorophenylcarbamate) column with 30% 2-propanol/1% n-butylamine while a single peak was observed under the same conditions on cellulose tris(3,5-dimethylphenylcarbamate) column. Experimental parameters were arbitrarily set at 150 bar outlet pressure, 40 °C temperature and 3 mL/min flow-rate.

γ-Lactam-Based Antifungal Compounds against the Wheat Pathogen Zymoseptoria tritici.

As new environmentally friendly and effective antifungal agents are deeply needed, efficient ecofriendly strategies were designed to access two series of compounds inspired from natural γ-lactams. Designed compounds were fully characterized and evaluated as antifungal candidates against Zymoseptoria tritici, the main pathogen on wheat crops. The targeted derivatives were prepared from natural resources using green solvents, simple procedures, and limited purification steps. These bio-inspired compounds revealed as good candidates for further development of efficient crop protection products. Indeed, the HIT compounds exhibited IC50 around 1 µg/mL and were more active than the references tebuconazole and bixafen towards some multidrug-resistant strains. Two dozen of derivatives have been obtained for each series and allowed to establish early structure-activity relationships useful for the development of next generation of γ-lactam derivatives with improved efficacy.

Electrophoretic separation of multiple chiral center analyte with a three cyclodextrins mixture.

A capillary electrokinetic chromatography method (CEKC) was developed for complete stereoisomeric separation of a neutral, hydrophobic, multiple chiral center dihydropyridone analogue, a drug candidate proposed in type 2 diabetes treatment. A background electrolyte comprising three cyclodextrins was found to successfully separate the eight isomers. First an anionic cyclodextrin, the SBE-ß-CD, was selected to allow the chiral separation of our neutral compound and partial resolutions of the eight isomers were obtained. Then, the effects of different parameters such as the nature and concentration of the other cyclodextrins added and pH of the buffer were examined. Finally, a triple CD-system consisted of 15 mM SBE-ß-CD plus 15 mM Î³-CD and 40 mM HP-γ-CD in a 50 mM borate background electrolyte at pH 10, was found to successfully separate the eight isomers. Last, the selectivity and limits of detection and quantification were evaluated for this optimized method.

Sesamol-based terpenoids as promising bio-sourced crop protection compounds against the wheat pathogen Zymoseptoria tritici.

BACKGROUND: Research into environmentally friendly alternatives to conventional plant protection products, to promote sustainable agriculture and healthy food, is strongly encouraged. RESULTS: In this context, 20 naturally occurring terpenoids and phenolic compounds were selected and evaluated in vitro as crop protection compounds against Zymoseptoria tritici, the causal agent of Septoria tritici blotch of wheat. After selection of the most active compounds, some hemisynthetic modifications were conducted to modify their lipophilicity. These modifications led to the discovery of sesamol esters as promising antifungal agents, with IC50 around 10 µg/mL and a total absence of cytotoxicity against human cells. CONCLUSION: These sesamol-based derivatives should be selected for further evaluations in planta to validate their use as wheat crop protection agents. Moreover, the importance of a balanced hydrophily/lipophilicity ratio should be further studied. © 2021 Society of Chemical Industry.

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.

Design, synthesis and evaluation of hydrazine and acyl hydrazone derivatives of 5-pyrrolidin-2-one as antifungal agents.

Twenty-eight 5-pyrrolidine-2-ones decorated by hydrazine or acyl hydrazones groups have been designed, synthesized and evaluated as antifungal agents on a panel of twelve fungal strains and three non albicans candida yeasts species which have demonstrated reduced susceptibility to commonly used antifungal drugs. Half of the target compounds exhibited good to high antifungal activities on at least one strain with MIC50 lower than the control antifungal agent - hymexazol or ketoconazole. 5-Arylhydrazino-pyrrolidin-2-ones were found active and the -NH-NH- linker proved to be essential to maintain the antifungal potential. Compound 2a is a broad-spectrum antifungal, active on 60% of the tested strains. Replacing the hydrazine linker by an acylhydrazone one narrowed the spectrum of activity but pyroglutamylaryl hydrazones, mainly aromatic ones, exhibited good activity, adequate "fungicide-like" properties and were devoted of cytotoxicity.

Design, synthesis and antifungal activity of pterolactam-inspired amide Mannich bases.

Pterolactam (5-methoxypyrrolidin-2-one) is a heterocycle naturally occurring in plants. In an attempt to identify antifungal agents, a series of novel Mannich bases of amide derivated from Pterolactam have been designed, synthesized and their antifungal activities were evaluated on a panel of nine fungal strains and three non albicans candida yeasts species which have demonstrated reduced susceptibility to commonly used antifungal drugs. A third of the target compounds exhibited good to high antifungal activities on at least one strain with EC50 lower than the control antifungal agent. N,N'-aminals derivated from Pterolactam proved to be good candidates for the development of biosourced fungicides, with compound 3o being the most broader-spectrum agent, active against five strains and devoted of any cytotoxicity.

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.

Antagonists of the adenosine A2A receptor based on a 2-arylbenzoxazole scaffold: Investigation of the C5- and C7-positions to enhance affinity.

We have recently reported a series of 2-furoyl-benzoxazoles as potential A2A adenosine receptor (A2AR) antagonists. Two hits were identified with interesting pharmacokinetic properties but were find to bind the hA2AR receptor in the micromolar-range. Herein, in order to enhance affinity toward the hA2AR, we explored the C5- and C7-position of hits 1 and 2 based on docking studies. These modifications led to compounds with nanomolar-range affinity (e.g. 6a, Ki = 40 nM) and high antagonist activity (e.g. 6a, IC50 = 70.6 nM). Selected compounds also exhibited interesting in vitro DMPK (Drug Metabolism and Pharmacokinetics) properties including high solubility and low cytotoxicity. Therefore, the benzoxazole ring appears as a highly effective scaffold for the design of new A2A antagonists.

Development and validation of a reversed-phase HPLC method for the quantification of paclitaxel in different PLGA nanocarriers.

A reversed-phase high-performance liquid chromatography (RP-HPLC) method has been developed and validated for the quantification of paclitaxel encapsulated in biodegradable poly(lactic-co-glycolic) (PLGA) copolymer nanoparticles. This simple (isocratic mode, without additive) and rapid (retention time of the paclitaxel under 4 min) methodology permits the detection of low quantities of paclitaxel in nanoparticulate formulations and the determination of the encapsulation efficiency (EE). Analysis was achieved on an octadecyl stationary phase. The isocratic mobile phase consisted of acetonitrile:water 80:20 (v/v) (flow rate = 0.8 mL/min). Stability of free paclitaxel was preliminary studied in those chromatographic conditions. The calibration curve was linear in the concentration range of 2-10 µg/mL (R2  = 0.9994). The method was specific with valuable trueness, repeatability (intra-day precision) and intermediate precision (inter-day precision) based on relative standard deviation (RSD) values (less than 2%). The limits of detection (LOD) and quantification (LOQ) were 0.56 and 1.85 ng/mL, respectively. This developed method was successfully employed for quantifying paclitaxel in PLGA 50:50 co-polymer nanoparticles. The accurate knowledge of the encapsulated paclitaxel concentration is essential to define the quantities of PLGA nanoparticles necessary to achieve the in vitro cell viability study.

6-Sulfonylbenzothiazolones as potential scaffolds for the design of 5-HT6 ligands.

5-HT6 Receptors are relatively recently discovered receptors that interact with cholinergic, glutamatergic, GABAergic and dopaminergic transmission systems. These receptors have been implicated in the CNS system as therapeutic targets in applications such as psychosis, reduction of body weight or Alzheimer's disease. As part of our efforts to develop 5-HT6 antagonists, we explored the benzothiazolone scaffold substituted in position 3 or 6 respectively with ethylamino chains and an aromatic ring connected through a sulfonyl linker. Final compounds were evaluated in radioligand binding assays for their ability to interact with 5-HT6 receptors. Their potential cytotoxic effects were determined on the human neuroblastoma cell line SY5Y. They showed very low cytotoxicity, and one of them has submicromolar affinity for 5-HT6 receptors.

Evaluation and comparison of three different separation techniques for analysis of retroamide enantiomers and their biological evaluation against h-P2X7 receptor.

The P2X receptors are seven-transmembrane domain G protein-coupled receptors and the 7 subtypes of P2X receptors identified in humans, and named P2X1 to P2X7, are channel receptors whose endogenous ligand is ATP. New antagonists of the P2X7 receptor were developed, since this purinergic receptor was highlighted to be involved in many diseases such as different types of pain, cancer, ischemia, neurodegenerative diseases (including Parkinson's and Alzheimer's diseases) characterized by inflammatory processes. With the aim of evaluate the impact of chirality on the pharmacological activity of a new P2X7R antagonist, a semi-preparative method was developed in supercritical fluid chromatography (SFC). Among four polysaccharide based chiral stationary phases: Chiralcel OD-H and OJ-H and Chiralpak AS-H and AD-H, the last one namely amylose tris (3,5-dimethylphenylcarbamate) with a mobile phase consisted of carbon dioxide-ethanol (80:20, v/v), led to the successful separation of the enantiomers in short run time and with good resolution. Limits of detection and quantification were calculated and were found equal for compound 1, to 1.37 µM and 4.57 µM respectively, for peak 1 and were equal to 1.60 µM and 5.30 µM respectively, for peak 2 at λ=210 nm. Before carrying out the pharmacological evaluation of each enantiomer, two complementary methodologies, e.g. liquid chromatography and capillary electrophoresis were performed in parallel to improve the limits of detection and quantification to assess the enantiomeric purity. HPLC using a Chiralpak AD stationary phase led to four times lower limits of detection and quantification with regard to SFC. In the same time, capillary electrophoresis involving dual cyclodextrins system constituted of a SBE-ß-CD and a MM-ß-CD mixture enhanced the signal-to-noise ratio and led to similar limits of detection and quantification with regard to SFC. No trace of the other enantiomer was found in the isolated one. Biological activities of individual enantiomers were then evaluated and revealed no cytotoxicity against cell lines and a significant difference in terms of their IC50 values with respect to the investigated racemate (6.43 µM): 3.49 µM for the (R)-enantiomer and >10(-4)µM for the (S)-enantiomer, for compound 1, showing that, this antagonist activity is stereospecific.

Synthesis and pharmacological evaluation of benzannulated derivatives as potent and selective sigma-1 protein ligands.

The σ1 proteins are considered to be a new class of target structures for several central nervous system disorders, including depression, anxiety, psychosis, and Parkinson's and Alzheimer's diseases. Recently, the involvement of these receptors in neuropathic pain and cancer has also been observed. So far, only a few ligands are in clinical trials. In a continuation of our previous studies on the development of σ1 ligands, a new series of benzannulated heterocycles was designed and synthesised. In vitro competition binding assays showed that many of them possessed high σ1 receptor affinity (Ki = 0.6-10.3 nM), and good σ2/σ1 subtype selectivity, without cytotoxic effects on SY5Y cells (human neuroblastoma cell line).