CycloLab R and D Ltd

Budapest, Hungary

CycloLab R and D Ltd

Budapest, Hungary
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Nemeth K.,Hungarian Academy of Sciences | Domonkos C.,Hungarian Academy of Sciences | Sarnyai V.,Hungarian Academy of Sciences | Szeman J.,CycloLab R andD Ltd. | And 3 more authors.
Journal of Pharmaceutical and Biomedical Analysis | Year: 2014

The resolution power of permethylated 6-monoamino-6-monodeoxy-βCD (PMMABCD) - a single isomer, cationic CD derivative - developed previously for chiral analyses in capillary electrophoresis was further studied here. Dansylated amino acids (Dns-AA) were chosen as amphoteric chiral model compounds. Changes in the resolutions of Dns-AAs by varying pH and selector concentrations were investigated and correlated with their structures and chemical properties (isoelectric point and lipophilicity). Maximal resolutions could be achieved at pH 6 or pH 4. The separations improved with increasing concentration of the selector. Baseline or substantially better resolution for 8 pairs of these Dns-AAs could be achieved. Low CD concentration was enough for the separation of the most apolar Dns-AAs. Chiral discrimination ability of PMMABCD was demonstrated by the separation of an artificial mixture of 8 Dns-AA pairs. © 2014 Elsevier B.V.

Nemeth K.,Hungarian Academy of Sciences | Tarkanyi G.,Hungarian Academy of Sciences | Varga E.,CycloLab R and D Ltd. | Imre T.,Hungarian Academy of Sciences | And 7 more authors.
Journal of Pharmaceutical and Biomedical Analysis | Year: 2011

Capillary electrophoresis (CE) methods for chiral resolution of five antimalarial drugs (primaquine, tafenoquine, mefloquine, chloroquine and quinacrine) were developed by using a wide selection of neutral and anionic cyclodextrin (CD) derivatives. The use of sulfobutyl-β-CD and carboxymethyl-β-CD (CMBCD) resulted in good resolution of quinacrine and tafenoquine, respectively. New results are presented for resolutions of chloroquine and mefloquine. Application of carboxyalkyl- and sulfobutyl-CD derivatives provided improved resolution for primaquine. The impurity in primaquine sample detected by CE was identified as quinocide by MS and NMR. CMBCD provided not only the best separation of primaquine from quinocide but also the simultaneous complete resolution of both compounds. © 2010 Elsevier B.V.

Fodor G.,University of Szeged | Ilisz I.,University of Szeged | Szeman J.,CycloLab R and D Ltd | Ivanyi R.,CycloLab R and D Ltd | And 5 more authors.
Chromatographia | Year: 2010

Direct liquid chromatographic methods were developed to investigate the enantioseparation of 19 β-Lactams on three cyclodextrin-bonded chiral stationary phases: permethyl-β-cyclodextrin, β-cyclodextrin and R,S-hydroxypropyl-β-cyclodextrin, prepared by a novel synthetic route. 17 of the 19 b-lactam stereoisomers were partially or baseline-separated on at least one of the tested chiral stationary phases. The influence of the structures of the β-Lactams (the positions and types of the substituents, the size of the attached rings) on the enantiomer separation is discussed. The permethylated β-cyclodextrin selector proved to be the most effective one for the tested analytes. © 2010 Vieweg+Teubner | GWV Fachverlage GmbH.

Ilisz I.,University of Szeged | Ivanyi R.,CycloLab R and D Ltd | Pataj Z.,University of Szeged | Kupai J.,Budapest University of Technology and Economics | And 4 more authors.
Chromatographia | Year: 2010

Direct capillary zone electrophoretic methods were developed for the separation of the enantiomers of 1-(α-aminoarylmethyl)-2-naphthol and 2-(a-aminoarylmethyl)-1-naphthol analogues. The effects of selector and buffer concentrations, electrolyte pH and applied voltage on the separation efficiency were studied. Variation of the electrophoretic conditions with the application of negative polarity, hydrodynamic injection, an unmodified silica capillary, different buffers and sulfated cyclodextrins and (S,S)-dimethylpyridino-18- crown-6 ether as chiral selectors led to the baseline resolution of all the compounds investigated. © 2010 Vieweg+Teubner | GWV Fachverlage GmbH.

Sohajda T.,Semmelweis University | Varga E.,CycloLab R and D Ltd | Ivanyi R.,CycloLab R and D Ltd | Fejos I.,Semmelweis University | And 3 more authors.
Journal of Pharmaceutical and Biomedical Analysis | Year: 2010

In this work, the enantiomeric separation of three vinca alkaloid enantiomers (vincamine, vinpocetine and vincadifformine) has been investigated in an aqueous capillary electrophoresis (CE) system using cyclodextrins (CDs). The investigated CDs were the native α-, β-, and γ-CDs and their hydroxypropylated, randomly methylated, carboxymethylated and sulfobutylated derivatives. The first part of this study consisted of the determination of the apparent averaged complex stability constants with the selected CDs. Several parameters, such as the nature and the concentration of the CD, were studied and were found to have a significant effect on the enantiomeric resolution for all studied compounds. All three vinca alkaloids were successfully enantioseparated with CDs where different migration orders were observed in case of several CDs depending on the cavity size or substituent of the host. Chiral separation and determination of the stability constants were also performed with NMR spectroscopy which confirmed the CE results. Averaged stoichiometries of the complexes were determined using the Job plot method resulting in a 1:1 complex irrespective of the alkaloid enantiomers or cyclodextrin derivative. The structures of the inclusion complexes were elucidated using 2D ROESY NMR spectroscopy. On the basis of NMR results reversal of enantiomer migration order was clarified in various cases. © 2010 Elsevier B.V.

Neumajer G.,Semmelweis University | Sohajda T.,Semmelweis University | Sohajda T.,CycloLab R and D Ltd | Darcsi A.,Semmelweis University | And 4 more authors.
Journal of Pharmaceutical and Biomedical Analysis | Year: 2012

The enantiomers of dapoxetine, a serotonin transporter inhibitor for the treatment of premature ejaculation have been separated by cyclodextrin modified capillary zone electrophoresis using uncoated fused-silica capillary. Over 20 cyclodextrins were screened as chiral selectors, investigating the stability of the inclusion complexes and enantioseparating properties. According to the preliminary experiments as chiral selector randomly methylated-γ-cyclodextrin was chosen. The basic chemical and instrumental parameters of enantioseparation as concentration of buffer, chiral selector and organic additive, pH, temperature and applied voltage were optimized afterwards using an orthogonal experimental design. Using this methodology not only the optimal parameter values for chiral separation (15 °C, +15. kV, 70. mM acetate, 20. v/v% MeOH, pH* =4.5, 3. mM methylated-γ-CyD) but also the significance order of factors on resolution was determined. Applying these parameters an optimal resolution of 7.01 was achieved. The optimized method was then validated according to the ICH guideline Q2 (R1) with regard to repeatability, linearity range, LOD, LOQ, accuracy and robustness. © 2011 Elsevier B.V.

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