Evaluation of three neutral capillary coatings for the determination of analyte-cyclodextrin binding constants by affinity capillary electrophoresis. Application to N,N'-disubstituted piperazine derivatives

The performances of three neutral static coatings (hydroxypropyl cellulose, polyethylene oxide and poly(N,N-dimethylacrylamide) have been evaluated in order to determine the binding constants of the complexes formed between four polycationic compounds (piperazine derivatives) and four cyclodextrins of pharmaceutical interest (β-CD, HP-β-CD, Me-β-CD and sulfobutyl ether-β-CD) by affinity capillary electrophoresis. The physically-adsorbed poly(N,N-dimethylacrylamide) coating proves to be the more efficient to mask the silanol groups of the capillary wall since the lowest electroosmotic flow was measured for this coating. Moreover, it drastically reduces the adsorption of the compounds since it allows a correct repeatability of their migration time, higher efficiencies of the peaks and no baseline shift. Then, it was verified for four complexes that this coating allows a correct determination of the binding constants avoiding the CD adsorption which is responsible of an undervaluation of binding constants. The highest binding constants are obtained using the anionic sulfobutyl ether-β-CD (SBE-β-CD). The structure of the complex formed between the tacrine derivative and the SBE-β-CD was further investigated through 2D ROESY NMR experiments and structure-binding constant relationships. Results suggest that the inclusion in the SBE-β-CD cavity occurs through the aliphatic ring portion of the tacrine moiety.

A method for the simultaneous determination of chlorogenic acid and sesquiterpene lactone content in industrial chicory root foodstuffs

A method for the simultaneous determination of free chlorogenic acids (CGA) and sesquiterpene lactones (STL) in chicory root and its dried (flour) and roasted (grain) forms is described. The method uses one extraction and one analysis for all chicory root products. Various solvents with low to high polarity, such as methanol, chloroform, or n-hexane, were tested alone, in combination in different proportions or with acidified or neutral aqueous solvent. The water/chloroform/methanol (30/30/40, v/v/v) mixture generated the best extraction yield, 21% higher than alcohol mixtures. The profiling of CGA and STL content was performed through a conventional HPLC-DAD method using a PFP core shell column in a fast single run. Good retention time and area repeatability (RDD mean % 0.46 and 5.6, resp.) and linearity (R2≥0.96) were obtained. The STL and chlorogenic acids levels determined were 254.7 and 100.2 μg/g of dry matter in the root, 792.5 and 1,547 μg/g in flour, and 160.4 and 822.5 μg/g in the roasted grains, respectively. With an average recovery of 106% and precision of 90%, this method is rapid, reproducible, and straightforward way to quantify the chlorogenic acids and STL in chicory raw material and end products.

Label-free characterization of carbonic anhydrase-novel inhibitor interactions using surface plasmon resonance, isothermal titration calorimetry and fluorescence-based thermal shift assays

This work describes the development of biophysical unbiased methods to study the interactions between new designed compounds and carbonic anhydrase II (CAII) enzyme. These methods have to permit both a screening of a series of sulfonamide derivatives and the identification of a lead compound after a thorough study of the most promising molecules. Interactions data were collected using surface plasmon resonance (SPR) and thermal shift assay (TSA). In the first step, experiments were performed with bovine CAII isoform and were extended to human CAII. Isothermal titration calorimetry (ITC) experiments were also conducted to obtain thermodynamics parameters necessary for the processing of the TSA data. Results obtained with this reference methodology demonstrate the effectiveness of SPR and TSA. KD values obtained from SPR data were in perfect accordance with ITC. For TSA, despite the fact that the absolute values of KD were quite different, the same affinity scale was obtained for all compounds. The binding affinities of the analytes studied vary by more than 50 orders of magnitude; for example, the KD value determined by SPR were 6 ± 4 and 299 ± 25 nM for compounds 1 and 3, respectively. This paper discusses some of the theoretical and experimental aspects of the affinity-based methods and evaluates the protein consumption to develop methods for the screening of further new compounds. The double interest of SPR, that is, for screening and for the quick thorough study of the interactions parameters (ka , kd , and KD ), leads us to choose this methodology for the study of new potential inhibitors.

Optimization of the enantioseparation of a diaryl-pyrazole sulfonamide derivative by capillary electrophoresis in a dual CD mode using experimental design

A CE method using dual cationic and neutral cyclodextrins (CD) was optimized for the enantiomeric separation of a compound presenting a diaryl sulfonamide group. Preliminary studies were made to select the optimal CDs and pH of the BGE. Two CDs (amino-β-CD and β-CD) were selected to separate the enantiomers in a 67 mM phosphate buffer at pH 7.4. However, the repeatability of the analyses obtained on bare-fused silica capillary was not acceptable owing to the adsorption of the amino-β-CD to the capillary. To prevent this, a dynamic coating of the capillary was used employing five layers of ionic-polymer (poly(diallyldimethylammonium) chloride (PDADMAC) and poly(sodium 4-styrenesulfonate). The efficiency of the coating was assessed by measuring the EOF stability. Repeatability of the injections was obtained when intermediate coating with PDADMAC was performed between each run. Secondly, this enantioseparation method was optimized using a central composite circumscribed design including three factors: amino-β-CD and β-CD concentrations and the percentage of methanol. Under the optimal conditions (i.e. 16.6 mM of amino-β-CD, 2.6 mM of β-CD, 0% MeOH in 67 mM phosphate buffer (pH 7.4) as BGE, cathodic injection 0.5 psi, 5 s, separation voltage 15 kV and a temperature of 15°C), complete enantioresolution of the analyte was obtained. It is worth mentioning that the design of experiments (DOE) protocol employed showed a significant interaction between CDs, highlighting the utility of DOE in method development. Finally, small variations in the ionic-polymer concentrations did not significantly influence the EOF, confirming the robustness of the coating method.

New selective carbonic anhydrase IX inhibitors: synthesis and pharmacological evaluation of diarylpyrazole-benzenesulfonamides

Carbonic anhydrase (CA) IX expression is increased upon hypoxia and has been proposed as a therapeutic target since it has been associated with poor prognosis, tumor progression and pH regulation. We report the synthesis and the pharmacological evaluation of a new class of human carbonic anhydrase (hCA) inhibitors, 4-(5-aryl-2-hydroxymethyl-pyrazol-1-yl)-benzenesulfonamides. A molecular modeling study was conducted in order to simulate the binding mode of this new family of enzyme inhibitors within the active site of hCA IX. Pharmacological studies revealed high hCA IX inhibitory potency in the parameters nanomolar range. This study showed that the position of sulfonamide group in meta of the 1-phenylpyrazole increase a selectivity hCA IX versus hCA II of our compounds. An in vitro antiproliferative screening has been performed on the breast cancer MDA-MB-231 cell using doxorubicin as cytotoxic agent and in presence of selected CA IX inhibitor. The results shown that the cytotoxic efficiency of doxorubicin in an hypoxic environment, expressed in IC50 value, is restored at 20% level with 1μM CA IX inhibitor.

In vitro pharmacokinetic profile of a benzopyridooxathiazepine derivative using rat microsomes and hepatocytes: identification of phases I and II metabolites

In the present study, the in vitro metabolic behavior of a benzopyridooxathiazepine (BZN), a potent tubulin polymerization inhibitor, was investigated by liquid chromatography-UV detection (LC-UV). First, simple and fast LC-UV methods have been optimized and validated to evaluate the pharmacokinetic profile of BZN using rat liver microsomes or hepatocytes primary cultures suspensions. Whatever the medium investigated, baseline resolution between the internal standard and BZN was achieved in a run time less than 15min using a Symmetry ODS column (150mm×4.6mm i.d., 5μm) and a mobile phase consisting of acetonitrile/water/formic acid 60:40:0.1 (v/v/v). Linearity was assessed in the 0.1-50μM and in the 0.05-5μM concentration ranges, respectively, in microsomal and hepatocyte matrix. According to the novel strategy based on the build of the accuracy profile, total error of the developed methods was included within the ±10% limits of acceptance. Then, from incubation of BZN with both liver microsomes and or hepatocytes, structural informations on phase I and phase II metabolites were acquired using liquid chromatography coupled to electrospray orbitrap mass spectrometer (LC-MS). Mass spectrum, double bond equivalent and elemental composition were useful data to access to the chemical structure of each metabolite. In microsomal suspension, four main metabolites were observed including monohydroxylation and dihydroxylation of the benzopyridooxathiazepine core, demethylation of the methoxyphenyl moiety, as well as their combinations. The phase II metabolites detected in hepatocytes suspension were the glucuronide adducts of both demethylated BZN and mono-oxygenated BZN. Based on the structural elucidation of the metabolites detected, we proposed an in vitro metabolic pathway of BZN, a new tubulin polymerization inhibitor.

Evaluation of decontamination efficacy of cleaning solutions on stainless steel and glass surfaces contaminated by 10 antineoplastic agents

OBJECTIVES

The handling of antineoplastic agents results in chronic surface contamination that must be minimized and eliminated. This study was designed to assess the potential of several chemical solutions to decontaminate two types of work surfaces that were intentionally contaminated with antineoplastic drugs.

METHODS

A range of solutions with variable physicochemical properties such as their hydrophilic/hydrophobic balance, oxidizing power, desorption, and solubilization were tested: ultrapure water, isopropyl alcohol, acetone, sodium hypochlorite, and surfactants such as dishwashing liquid (DWL), sodium dodecyl sulfate (SDS), Tween 40, and Span 80. These solutions were tested on 10 antineoplastic drugs: cytarabine, gemcitabine, methotrexate, etoposide phosphate, irinotecan, cyclophosphamide, ifosfamide, doxorubicin, epirubicin, and vincristine. To simulate contaminated surfaces, these molecules (200ng) were deliberately spread onto two types of work surfaces: stainless steel and glass. Recovered by wiping with a specific aqueous solvent (acetonitrile/HCOOH; 20/0.1%) and an absorbent wipe (Whatman 903®), the residual contamination was quantified using high-performance liquid chromatography (HPLC) coupled to mass spectrometry. To compare all tested cleaning solutions, a performance value of effectiveness was determined from contamination residues of the 10 drugs.

RESULTS

Sodium hypochlorite showed the highest overall effectiveness with 98% contamination removed. Ultrapure water, isopropyl alcohol/water, and acetone were less effective with effectiveness values of 76.8, 80.7, and 40.4%, respectively. Ultrapure water was effective on most hydrophilic molecules (97.1% for cytarabine), while on the other hand, isopropyl alcohol/water (70/30, vol/vol) was effective on the least hydrophilic ones (85.2% for doxorubicin and 87.8% for epirubicin). Acetone had little effect, whatever the type of molecule. Among products containing surfactants, DWL was found effective (91.5%), but its formulation was unknown. Formulations with single surfactant non-ionics (tween 40 and span 80) or anionic (SDS) were also tested. Finally, solutions containing 10(-2) M anionic surfactants and 20% isopropyl alcohol had the highest global effectiveness at around 90%. More precisely, their efficacy was the highest (94.8%) for the most hydrophilic compounds such as cytarabine and around 80.0% for anthracyclines. Finally, the addition of isopropyl alcohol to surfactant solutions enhanced their decontamination efficiency on the least hydrophilic molecules. Measured values from the stainless steel surface were similar to those from the glass one.

CONCLUSION

This study demonstrates that all decontamination agents reduce antineoplastic contamination on work surfaces, but none removes it totally. Although very effective, sodium hypochlorite cannot be used routinely on stainless steel surfaces. Solutions containing anionic surfactant such as SDS, with a high efficiency/safety ratio, proved most promising in terms of surface decontamination.

Synthesis, antiproliferative activity and tubulin targeting effect of acridinone and dioxophenothiazine derivatives

The synthesis of new acridinone and dioxophenothiazine derivatives along with their tubulin polymerization inhibitory and antiproliferative activities is reported. The analysis of correlation for cytotoxic and antitubulin potential of tested compounds showed that 4-methoxyphenylethyl derivatives 18a and 19a were highly cytotoxic but were regarded to have no significant antitubulin activity. However, the introduction of a 3-hydroxy substituent leading to compounds 18e and 19e, strongly increased the antitubulin potential but was associated with a loss of the antiproliferative activity. Modeling studies, topoisomerase inhibition assays and cell cycle analysis have been performed to better investigate the mechanism of action of such compounds.

Multiple-test assessment of devices to protect healthcare workers when administering cytotoxic drugs to patients

Purpose: Evaluation of containment safety devices designed and introduced to protect preparers and administrators of hazardous drugs, through a multiple-test assessment.

Methods: Six devices were compared: (1) Kis1 gravity-fed infusion set (Doran International, France), (2) Tevadaptor Spike Port Adapter (Teva Pharma AG, France), (3) Phaseal Infusion Adapter C100 (Carmel Pharma AB, France), (4) Codan Connect Z (Codan, France), (5) Pchimx with or without a cap (Doran International, France), and (6) Clave extension set 011-H1225 with or without Spiros (Hospira, France). Assessment of exposure to hazardous drugs was performed using quinine as fluorescent marker. Mechanical tests included tightness, tension tests, and estimation of the force required to connect the infusion device to the bag. Ergonomic tests were performed by six pharmaceutical technicians. Microbiological contamination was tested with media-fill, on connected bag.

Results: No cytotoxic contamination was detected when using Phaseal, Tevadaptor or the Clave extension set with Spiros, Pchimx with a cap or Connect Z devices. For mechanical tests, all devices complied with the norm. Microbiological growth was observed neither in bags nor in tubings. The ergonomic study revealed differences between the devices for potential cytotoxic contamination risk only, but not for handling.

Conclusions. The use of containment safety devices offers improved handling conditions of hazardous compounds. As this study takes various selection criteria into account, its results offer assistance in choosing the most suitable device.

Design, synthesis, and DNA-binding of N-alkyl(anilino)quinazoline derivatives

New N-alkylanilinoquinazoline derivatives 5, 12, 20, and 22 have been prepared from 4-chloro-6,7-dimethoxyquinazoline 3, 4-chloro-6,7-methylenedioxyquinazoline 19, and commercially available anilines. Differents classes of compounds substituted by an aryloxygroup (6a-c, 16a,b, and 17a,b), (aminophenyl)ureas (12a,b and 13a-f), anilines (4a-m, 20a,b), N-alkyl(aniline) (5a-m, 21a,b, 22a,d), and N-aminoalkyl(aniline) (22e-g) have been synthesized. These molecules were evaluated for their cytotoxic activities and as potential DNA intercalating agents. We studied the strength and mode of binding to DNA of these molecules by DNA melting temperature measurements, fluorescence emission, and circular dichroism. The results of various spectral and gel electrophoresis techniques obtained with the different compounds, in particular compounds 5g and 22f, revealed significant DNA interaction. These experiments confirm that the N-aminoalkyl(anilino)-6,7-dimethoxyquinazoline nucleus is an efficient pharmacophore to trigger binding to DNA, via an intercalative binding process.

Design, solid-phase synthesis, and biological evaluation of novel 1,5-diarylpyrrole-3-carboxamides as carbonic anhydrase IX inhibitors

Following previous studies we herein report the synthesis and the pharmacological evaluation of a new class of human carbonic anhydrase (hCA) inhibitors, 1,5-diarylpyrrole-3-carboxamides prepared by a solid-phase strategy involving a PS(HOBt) resin. A molecular modeling study was conducted in order to simulate the binding mode of this new family of enzyme inhibitors within the active site of hCA IX. This study revealed that the 3-position of the pyrrole was opened to the solvent, so we introduced an amino side-chain, protonated at physiological pH both to enhance the aqueous solubility and to decrease the cell membrane penetration. This strategy consisted of preparing membrane-impermeant inhibitors that may selectively target the tumor-associated hCA IX. Physico-chemical characterizations including aqueous solubility and lipophilic parameters are described. Pharmacological studies revealed high hCA IX inhibitory potency in the nanomolar range. Some compounds are selective for hCA IX displaying hCA I/hCA IX and hCA II/hCA IX ratios higher than 20 and 5, respectively.

Separation of nucleoside phosphoramidate diastereoisomers by high performance liquid chromatography and capillary electrophoresis

Separations of five diastereoisomers of nucleoside phosphoramidate derivatives (pronucleotides) were performed by both HPLC method using derivatized cellulose and amylose chiral stationary phases and CE method using anionic cyclodextrins added in the background electrolyte (BGE). An optimal baseline separation (Rs > 1.5) was readily obtained with all silica-based celluloses and amyloses using in a normal-phase methodology. Capillary electrophoresis was used as an alternative technique to HPLC for the separation of pronucleotides. The diastereoisomers were fully resolved with sulfated cyclodextrins at both BGE pH (2.5 and 6.2). Limits of detection and limits of quantification, calculated for both methods, are up to 200 times higher in CE separations than in HPLC separations. The analytical HPLC method was then applied in a preliminary study for the pronucleotide 1 quantification in cellular extract.

Design, synthesis and biological evaluation of substituted dioxodibenzothiazepines and dibenzocycloheptanes as farnesyltransferase inhibitors

A new series of FTase inhibitors containing a tricyclic moiety--dioxodibenzothiazepine or dibenzocycloheptane--has been designed and synthesized. Among them, dioxodibenzothiazepine 18d displayed significant inhibitory FTase activity (IC(50)=17.3 nM) and antiproliferative properties.

Determination of pKa values of benzoxa-, benzothia- and benzoselena-zolinone derivatives by capillary electrophoresis

Acidity constants of benzoxa-, benzothia- and benzoselena-zolinone derivatives were determined by capillary electrophoresis, potentiometry and spectrophotometry experiments. These three analytical techniques gave pK(a) results that were in good agreement. A convenient, accurate and precise method for the determination of pK(a) was developed to measure changes in acidity constants induced by heteroatom or 6-benzoyl substituted derivatives. pK(a) values were determined simultaneously for two compounds characterized by different electrophoretic mobility (micro(e)) and pK(a) value and in the presence of an analogous neutral marker.