References of "Servais, Anne-Catherine"
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See detailOptimization of an electrophoretic approach for the screening and the development of new antithrombotic drugs
Farcas, Elena ULg; Bouckaert, Charlotte; Servais, Anne-Catherine ULg et al

Conference (2017, June 20)

The discovery of lead compounds that can modulate the activity of a biological target is essential to provide efficient pharmacological tools and to serve as starting points for new drug generations ... [more ▼]

The discovery of lead compounds that can modulate the activity of a biological target is essential to provide efficient pharmacological tools and to serve as starting points for new drug generations. Fragment-based drug discovery (FBDD) approach is an attractive tool for the identification of new selective inhibitors of a target of interest, but its success largely depends on the ability to develop screening bioassays capable to detect and gauge weak affinity binders. To achieve this goal, we investigated capillary electrophoresis (CE) for identifying and ranking fragments from an initial library. Indeed, due to its ability to evaluate weak interactions, CE seems to be promising for fragment-based screening. This technique is a powerful analytical tool with a unique separation mechanism, speed, efficiency and versatility. Its main advantages are low protein consumption, higher throughput compared to NMR and X-ray crystallography and the fact that screening can be carried out using native protein in physiological solution without the need of immobilization. We developed a proof of concept study on thrombin, a serine protease implicated in the coagulation cascade using affinity capillary electrophoresis (ACE) for ranking fragments from an initial library. For this study, we followed a probe ligand, benzamidine, and we investigated interactions with the target by monitoring the changes of its electrophoretic mobility upon binding. The first step of this study consisted in the optimization of the experimental conditions suitable for the CE method (target and probe ligand concentrations, separation buffer composition, voltage, separation effective length, target partial filling…). Then, numerous thrombin inhibitors with a wide range of inhibitory potency (i.e. Ki 200 µM – 5 nM) were tested to validate our system demonstrating the possibility to fish binders in the optimized conditions. We also checked the absence of non-specific binding with the target using the inactivated enzyme at the binding site. It is noteworthy that in this operating system (ACE assay), binding occurs in free solution using physiological buffers, thus preventing artifacts that may result from target immobilization, which is a requirement for some techniques such as SPR. [less ▲]

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See detailOptimiaztion of an electrophoretic approach for the screening and the development of new antithrombotic drugs
Farcas, Elena ULg; Bouckaert, Charlotte; Servais, Anne-Catherine ULg et al

Poster (2017, June 19)

The discovery of lead compounds that can modulate the activity of a biological target is essential to provide efficient pharmacological tools and to serve as starting points for new drug generations ... [more ▼]

The discovery of lead compounds that can modulate the activity of a biological target is essential to provide efficient pharmacological tools and to serve as starting points for new drug generations. Fragment-based drug discovery (FBDD) approach is an attractive tool for the identification of new selective inhibitors of a target of interest, but its success largely depends on the ability to develop screening bioassays capable to detect and gauge weak affinity binders. To achieve this goal, we investigated capillary electrophoresis (CE) for identifying and ranking fragments from an initial library. Indeed, due to its ability to evaluate weak interactions, CE seems to be promising for fragment-based screening. This technique is a powerful analytical tool with a unique separation mechanism, speed, efficiency and versatility. Its main advantages are low protein consumption, higher throughput compared to NMR and X-ray crystallography and the fact that screening can be carried out using native protein in physiological solution without the need of immobilization. We developed a proof of concept study on thrombin, a serine protease implicated in the coagulation cascade using affinity capillary electrophoresis (ACE) for ranking fragments from an initial library. For this study, we followed a probe ligand, benzamidine, and we investigated interactions with the target by monitoring the changes of its electrophoretic mobility upon binding. The first step of this study consisted in the optimization of the experimental conditions suitable for the CE method (target and probe ligand concentrations, separation buffer composition, voltage, separation effective length, target partial filling…). Then, numerous thrombin inhibitors with a wide range of inhibitory potency (i.e. Ki 200 µM – 5 nM) were tested to validate our system demonstrating the possibility to fish binders in the optimized conditions. We also checked the absence of non-specific binding with the target using the inactivated enzyme at the binding site. It is noteworthy that in this operating system (ACE assay), binding occurs in free solution using physiological buffers, thus preventing artifacts that may result from target immobilization, which is a requirement for some techniques such as SPR. [less ▲]

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See detailWhole blood microsampling for the quantitation of estetrol without derivatization by liquid chromatography-tandem mass spectrometry
Nys, Gwenaël ULg; Gallez, Anne ULg; Kok, Miranda ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2017), 140

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See detailSeparation of FLEC diastereomers by CE vs. LC approaches in the context of neurometabolomics
Moldovan, Radu-Cristian ULg; Bodoki, Ede; Servais, Anne-Catherine ULg et al

Poster (2017, June)

Some of the D-amino acids (D-Ser, D-Asp, D-Glu) have gained an increasing attention during the last decades, due to the discovery of their role as neurotransmitters and their implication in different ... [more ▼]

Some of the D-amino acids (D-Ser, D-Asp, D-Glu) have gained an increasing attention during the last decades, due to the discovery of their role as neurotransmitters and their implication in different neurological pathologies (Alzheimer’s disease, schizophrenia etc.). Nevertheless, their use as biomarkers is particularly relevant when correlated with the levels of other neurotransmitters. In order to develop a fast and efficient separation method widely accessible for the quantitation of these molecules, we used only common separation tools such as RP-18 stationary phases for reversed phase liquid chromatography (RP-LC) or bare fused capillaries for capillary zone electrophoresis (CZE). For achieving chiral resolution, a derivatization procedure was implemented. (-)-FLEC was the chiral derivatization agent of choice due to its fast and quantitative reaction with primary and secondary amines and the ability of performing in-capillary derivatization. Moreover, the derivatization process implies only a simple mix of the sample and reagent, at room temperature. The separation of the FLEC derivatives of several biologically relevant D- and L- amino acids (Asp, Glu, Ser, Tyr, Trp, Phe, His) together with certain neurotransmitter molecules have been optimized using CZE or RP-LC, chiral resolution being achievable for all amino acids of interest. By the CZE approach the running buffer’s pH turned out to be critical in achieving baseline separation of the targeted analytes. The derivatives of most amino acids could be separated using 60mM acetate buffer at pH 5, while for Asp derivatives the separation could be achieved only at pH 4. Being stronger bases, a third run at a more alkaline pH was needed for the separation of the remainder neurotransmitters. Moreover, the implemented in-capillary derivatization allows a fast and fully automated separation procedure. As for the RP-LC approach 50 mM acetate buffer in combination with an organic modifier (methanol, acetonitrile or tetrahydrofuran (THF)) was tested as mobile phase using gradient elution. Once again, the strong influence of pH on the resolution was observed. The organic modifier nature was of critical importance, where only THF enabled baseline resolution for all amino acid derivatives. [less ▲]

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See detail(+) or (-)-1-(9-fluorenyl)ethyl chloroformate as chiral derivatizing agent: A review.
Moldovan, Radu-Cristian ULg; Bodoki, Ede; Servais, Anne-Catherine ULg et al

in Journal of Chromatography. A (2017), 1513

Over the last 30years, (+/-)-1-(9-fluorenyl)ethyl chloroformate ((+/-)-FLEC) was used as a chiral derivatizing agent in various analytical applications involving a wide range of endogenous, pharmaceutical ... [more ▼]

Over the last 30years, (+/-)-1-(9-fluorenyl)ethyl chloroformate ((+/-)-FLEC) was used as a chiral derivatizing agent in various analytical applications involving a wide range of endogenous, pharmaceutical and environmentally relevant molecules. This comprehensive review aims to present all the significant aspects related to the state of the art in FLEC labeling and subsequent chiral separation of the resulting diastereomers using LC, SFC and CE techniques. [less ▲]

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See detailCapillary electrophoresis in the context of drug discovery.
Farcas, Elena ULg; Pochet, Lionel; Crommen, Jacques ULg et al

in Journal of Pharmaceutical & Biomedical Analysis (2017)

Capillary Electrophoresis is a very efficient and resolutive separation technique used for many years in the analytical field. Despite all its assets, CE remains poorly used in drug discovery. This can be ... [more ▼]

Capillary Electrophoresis is a very efficient and resolutive separation technique used for many years in the analytical field. Despite all its assets, CE remains poorly used in drug discovery. This can be explained by the relatively low number of experienced CE practitioners, the maturity of HPLC in the pharmaceutical industry and some intrinsic limitations of the technique. The objective of this review is to focus our attention on recent developments of this technique in three different drug discovery areas: bioassays, drug-plasma interactions and drug metabolism studies. These developments were based on two important abilities of CE: the capacity to measure non-covalent interactions in solution and the ability to use a portion of the capillary as a reactor while the rest of the capillary is used for the separation of the product of the reaction. [less ▲]

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See detailSingle and dual cyclodextrins systems for the enantiomeric and diastereoisomeric separations of structurally related dihydropyridone analogues.
Delplanques, Thibaut; Boulahjar, Rajaa; Charton, Julie et al

in Electrophoresis (2017)

Cyclodextrin capillary electrophoresis methods (CD-CZE) were developed for complete enantiomeric and diastereoisomeric separations of a series of ten dihydropyridone analogues, of which eight were neutral ... [more ▼]

Cyclodextrin capillary electrophoresis methods (CD-CZE) were developed for complete enantiomeric and diastereoisomeric separations of a series of ten dihydropyridone analogues, of which eight were neutral, one was anionic and one was cationic. Ten different systems comprising one or two cyclodextrins were found to successfully separate the isomers thanks to a screening approach. Among the tested cyclodextrins, HS-gamma-CD, either in a single or in a dual system, in a phosphate buffer using capillaries dynamically coated with polyethylene oxide (PEO), and SBE-beta-CD, either in a single or in a dual system, in a borate buffer using uncoated capillaries, were the most selective selectors. The effects of different parameters such as the nature and concentration of the cyclodextrins, nature and concentration of the buffer, and voltage were examined. The precision and limits of detection and quantification were evaluated for the optimized methods. This article is protected by copyright. All rights reserved. [less ▲]

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See detailStudy of virus-like particles of human papillomavirus in capillary electrophoresis
Bettonville, Virginie ULg; Nicol, Jérôme; Furst, Tania et al

Poster (2017)

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See detailOPTIMIZATION OF A FULLY AUTOMATED ELECTROPHORETICALLY MEDIATED MICROANALYSIS SYSTEM FOR CYP1A1 ACTIVITY MONITORING
Farcas, Elena ULg; Servais, Anne-Catherine ULg; Lamalle, Caroline et al

Conference (2016, October 01)

Objective of the study Since CYP1A1, a member of cytochrome P450 superfamily, has been described to be over expressed in various types of cancer, our study was focused on the optimization of a fully ... [more ▼]

Objective of the study Since CYP1A1, a member of cytochrome P450 superfamily, has been described to be over expressed in various types of cancer, our study was focused on the optimization of a fully automated system for the monitoring of this particularly interesting enzyme. Moreover, the potentiality of this approach to screen CYP1A1 inhibitors was investigated. Materials and methods The experiments were carried out on a HP3DCE system using an on-column DAD. The EMMA procedure was performed by injecting a plug containing the co-factor(NADPH) and the substrate(7-ethoxycoumarin) between two plugs of CYP1A1 supersomes. The reaction was triggered by the application of a voltage switch. The voltage was then turned off to allow the metabolic reaction to occur. The separation of the components was then performed. Results Satisfying results were obtained using CYP1A1 at a concentration of 200 pmol/mL, while the incubation time was settled to 15 min. A DoE was performed to find the best mixing conditions. The amount of metabolite obtained was comparable to the one detected after conventional off-line metabolization. The ability of our system to monitor CYP1A1 inhibition was then proven with apigenin, a well-known CYP1A1 inhibitor. Conclusions The present study describes the development of a fully automatized in-capillary method for CYP1A1 activity monitoring and proves the potentialy of our system to be used for the screening of CYP1A1 inhibitors. The advantages of performing inline metabolization assays are mainly the miniaturization and the automatization of the process. Besides, the reagents consumption is drastically reduced due to the injection of few tens of nanoliters. [less ▲]

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See detailCapillary electrophoresis method to determine siRNA complexation with cationic liposomes
Furst, Tania ULg; Bettonville, Virginie ULg; Farcas, Elena ULg et al

in Electrophoresis (2016)

Small interfering RNA (siRNA) inducing gene silencing has great potential to treat many human diseases. To ensure effective siRNA delivery, it must be complexed with an appropriate vector, generally ... [more ▼]

Small interfering RNA (siRNA) inducing gene silencing has great potential to treat many human diseases. To ensure effective siRNA delivery, it must be complexed with an appropriate vector, generally nanoparticles. The nanoparticulate complex requires an optimal physiochemical characterization and the complexation efficiency has to be precisely determined. The methods usually used to measure complexation are gel electrophoresis and RiboGreen® fluorescence-based assay. However, those approaches are not automated and present some drawbacks such as the low throughput and the use of carcinogenic reagents. The aim of this work is to develop a new simple and fast method to accurately quantify the complexation efficiency. In this research, capillary electrophoresis (CE) was used to determine the siRNA complexation with cationic liposomes. The short-end injection mode applied enabled siRNA detection in less than 5 min. Moreover, the CE technique offers many advantages compared to the other classical methods. It is automated, does not require sample preparation and expensive reagents. Moreover, no mutagenic risk is associated to CE approach since no carcinogenic product is used. Finally, this methodology can also be extended to the characterization of other types of nanoparticles encapsulating siRNA, such as cationic polymeric nanoparticles. [less ▲]

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See detailApproches intégrées en Sciences Pharmaceutiques
Servais, Anne-Catherine ULg; Ziemons, Eric ULg

Conference (2016, May 13)

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See detailVolumetric Absorptive Microsampling for Hepcidin Peptide Extraction from Whole Blood
Houbart, Virginie ULg; COBRAIVILLE, Gaël ULg; Nys, Gwenaël ULg et al

in LCGC North America (2016), 34(5),

Whole blood analysis is an emerging trend in the field of bioanalysis. We developed a fast and simple protocol to extract and analyze a peptide, hepcidin, from whole blood. Sampling and extraction were ... [more ▼]

Whole blood analysis is an emerging trend in the field of bioanalysis. We developed a fast and simple protocol to extract and analyze a peptide, hepcidin, from whole blood. Sampling and extraction were carried out using volumetric absorptive microsampling (VAMS), a novel blood collection method that allows the sampling of a known blood volume independently from hematocrit. The composition of the extraction medium was optimized using an experimental design to get the most intense signal of hepcidin, considering different organic solvents and acidic additives. [less ▲]

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See detailEnantioselective capillary electrophoresis-mass spectrometry of amino acids in cerebrospinal fluid using a chiral derivatizing agent and volatile surfactant.
Prior, A.; Moldovan, Radu-Cristian ULg; Crommen, Jacques ULg et al

in Analytica Chimica Acta (2016), 940

The sensitivity of coupled enantioselective capillary electrophoresis-mass spectrometry (CE-MS) of amino acids (AAs) is often hampered by the chiral selectors in the background electrolyte (BGE). A new ... [more ▼]

The sensitivity of coupled enantioselective capillary electrophoresis-mass spectrometry (CE-MS) of amino acids (AAs) is often hampered by the chiral selectors in the background electrolyte (BGE). A new method is presented in which the use of a chiral selector is circumvented by employing (+)-1-(9-fluorenyl)ethyl chloroformate (FLEC) as chiral AA derivatizing agent and ammonium perfluorooctanoate (APFO) as a volatile pseudostationary phase for separation of the formed diastereomers. Efficient AA derivatization with FLEC was completed within 10 min. Infusion experiments showed that the APFO concentration hardly affects the MS response of FLEC-AAs and presents significantly less ion suppression than equal concentrations of ammonium acetate. The effect of the pH and APFO concentration of the BGE and the capillary temperature were studied in order to achieve optimized enantioseparation. Optimization of CE-MS parameters, such as sheath-liquid composition and flow rate, ESI and MS settings was performed in order to prevent analyte fragmentation and achieve sensitive detection. Selective detection and quantification of 14 chiral proteinogenic AAs was achieved with chiral resolution between 1.2 and 8.6, and limits of detection ranging from 130 to 630 nM injected concentration. Aspartic acid and glutamic acid were detected, but not enantioseparated. The optimized method was applied to the analysis of chiral AAs in cerebrospinal fluid (CSF). Good linearity (R(2) > 0.99) and acceptable peak area and electrophoretic mobility repeatability (RSDs below 21% and 2.4%, respectively) were achieved for the chiral proteinogenic AAs, with sensitivity and chiral resolution mostly similar to obtained for standard solutions. Next to l-AAs, endogenous levels of d-serine and d-glutamine could be measured in CSF revealing enantiomeric ratios of 4.8%-8.0% and 0.34%-0.74%, respectively, and indicating the method's potential for the analysis of low concentrations of d-AAs in presence of abundant l-AAs. [less ▲]

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See detailAnalysis of protamine peptides in insulin pharmaceutical formulations by capillary electrophoresis.
Lamalle, Caroline; Servais, Anne-Catherine ULg; Demelenne, Alice ULg et al

in Journal of Separation Science (2016), 39(6), 1189-94

Protamines are a group of highly basic peptides that are sometimes added to insulin formulations to prolong the pharmacological action. In this study, different methods were investigated to identify ... [more ▼]

Protamines are a group of highly basic peptides that are sometimes added to insulin formulations to prolong the pharmacological action. In this study, different methods were investigated to identify protamine in insulin formulations. Capillary electrophoresis in aqueous and non-aqueous media was tested to separate these peptides with very close amino acid sequences. Different buffers (phosphate or formate, both acidified) and various additives (principally negatively charged and neutral surfactants) were investigated to optimize peptide separation. Finally, a micellar electrokinetic capillary chromatography method using a capillary of 120 cm effective length and an aqueous background electrolyte made up of 100 mM phosphate buffer (pH 2) and 50 mM Thesit(R) gave the best results, providing the separation of the four major protamine peptides within 25 min. [less ▲]

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