Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
Peer Reviewed
See detailENANTIOSELECTIVE SYNTHESIS OF NCA (S)-L-([ALPHA-C-11]METHYL)-TRYPTOPHAN
Plenevaux, Alain ULg; Lemaire, Christian ULg; Delfiore, Guy et al

in Applied Radiation & Isotopes (1994), 45(6), 651-653

N.c.a. (S)-L-([alpha-C-11]methyl)-tryptophan was prepared by treatment at -78-degrees-C of (2S,3aR,8aS)-1,2-bis(-methoxycarbonyl)-1,2,3,3a,8,8a-hexahydropyrrolo[2, 3-b]-indole with lithium ... [more ▼]

N.c.a. (S)-L-([alpha-C-11]methyl)-tryptophan was prepared by treatment at -78-degrees-C of (2S,3aR,8aS)-1,2-bis(-methoxycarbonyl)-1,2,3,3a,8,8a-hexahydropyrrolo[2, 3-b]-indole with lithium diisopropylamide and [C-11]CH3I. After hydrolysis with HI and HPLC purification, the title compound was isolated with a radiochemical yield of 36% (EOB corrected) within 22 min; e.e. was shown > 97% (n = 20); specific activity was ranging between 0.8 and 1.2 Ci (30-45 GBq)/mu mol EOB. [less ▲]

Detailed reference viewed: 34 (1 ULg)
Peer Reviewed
See detailEnantioselective synthesis of thioesters as substrates for high-through put screening assays of Penicillin Binding Proteins
Simon, Justine ULg; Zervosen, Astrid ULg; Bouillez, André ULg et al

Poster (2013, June 19)

Excessive utilization of beta-lactam antibiotics like penicillin has created drug-resistant strains in bacteria. One of the main mechanisms of resistance is the production of drug resistant Penicillin ... [more ▼]

Excessive utilization of beta-lactam antibiotics like penicillin has created drug-resistant strains in bacteria. One of the main mechanisms of resistance is the production of drug resistant Penicillin Binding Proteins (PBPs) and the over expression of these proteins. The transglycosidase and transpeptidase activities of PBPs catalyze the last two steps of peptidoglycan biosynthesis, which is unique to bacteria, and lies outside the cytoplasmic membrane. PBPs are interesting targets and efforts are still done to find new inhibitors. <br />A thioesterase activity has been described for various PBPs. For example, the thioester S2d is a substrate of PBP R39 of Actinomadura and of PBP2x of Streptococcus pneumoniae. The utilization of thioesters allows a rapid screening of active compounds in high-through put screening assays. Furthermore detailed kinetic studies using thioesters as reporter substrates are also possible. <br />Here we will present the enantioselective synthesis of the thioesters and their application as substrates in high through put screening assays. [less ▲]

Detailed reference viewed: 106 (38 ULg)
Full Text
Peer Reviewed
See detailEnantioseparation of Acidic Drugs by Capillary Electrophoresis Using Dual Systems with Mixtures of Charged and Neutral Cyclodextrins
Fillet, Marianne ULg; Fotsing, Lucas ULg; Schomburg, G. et al

in Biomedical Chromatography : BMC (1998), 12(3, May-Jun), 131-2

Detailed reference viewed: 45 (1 ULg)
Peer Reviewed
See detailEnantioseparation of aminoglutethimide with cyclodextrins in capillary electrophoresis and studies of selector-selectand interactions using NMR spectroscopy and electrospray ionization mass spectrometry.
Chankvetadze, Bezhan; Fillet, Marianne ULg; Burjanadze, N. et al

in Enantiomer (2000), 5(3-4), 313-22

The enantiomers of aminoglutethimide [2-(p-aminophenyl)-2-ethylglutarimide, AGT] can be resolved in CE using all of three most commonly used native cyclodextrins (CD): alpha-, beta-, and gamma-CDs. The ... [more ▼]

The enantiomers of aminoglutethimide [2-(p-aminophenyl)-2-ethylglutarimide, AGT] can be resolved in CE using all of three most commonly used native cyclodextrins (CD): alpha-, beta-, and gamma-CDs. The migration order of the enantiomers was opposite using beta-CD compared to alpha- and gamma-CDs as chiral selectors. In order to examine some underlying mechanisms of the chiral recognition the interaction of AGT with the chiral selectors was studied with one- and two-dimensional NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS). The Job's and Scott's plots constructed based on the complexation-induced chemical shifts (CICS) observed in NMR spectra provided some preliminary information on the stoichiometry of the intermolecular complexes but did not seem to be absolutely reliable perhaps because the self-association of the analyte molecules and the formation of multiple type selectand-selector complexes. Therefore, an attempt was made to characterize the complexes using ESI-MS. This technique provided information on the stoichiometry and relative affinity constants of selector-selectand complexes. The information on the structure of complexes in the solution was obtained using one-dimensional rotating frame nuclear Overhauser enhancement (1D-ROESY) NMR spectroscopic studies. Significant differences were observed between the structures of the AGT complexes with beta- and gamma-CD. [less ▲]

Detailed reference viewed: 50 (1 ULg)
Full Text
Peer Reviewed
See detailEnantioseparation of N-derivatized amino acids by micro-liquid chromatography using carbamoylated quinidine functionalized monolithic stationary phase.
Wang, Qiqin; Feng, Jun; Han, Hai et al

in Journal of chromatography. A (2014), 1363

In order to obtain satisfactory column permeability, efficiency and selectivity for micro-HPLC, a capillary monolithic column containing O-9-[2-(methacryloyloxy)-ethylcarbamoyl]-10,11-dihydroquinidine ... [more ▼]

In order to obtain satisfactory column permeability, efficiency and selectivity for micro-HPLC, a capillary monolithic column containing O-9-[2-(methacryloyloxy)-ethylcarbamoyl]-10,11-dihydroquinidine (MQD) as chiral selector was re-optimized. The monolithic column was used to successfully enantioresolve a wide range of N-derivatized amino acids including alanine, leucine, methionine, threonine, phenylalanine, valine, serine, isoleucine, tryptophan, and cysteine. The influence of mobile phase parameters, such as the organic solvent type and concentration, the apparent pH, and buffer concentration, on retention and enantioseparation of N-derivatized amino acids has been investigated. 3,5-dinitrobenzoyl-amino acids and 3,5-dichlorobenzoyl-amino acids were resolved into enantiomers with exceptionally high selectivity and resolution. The chemoselectivity of the monolithic column for a multicomponent mixture of N-derivatized amino acids was also investigated. A mixture of three pairs of 3,5-dichlorobenzoyl-amino acids could be fully resolved in 22.5 min. [less ▲]

Detailed reference viewed: 17 (0 ULg)
Peer Reviewed
See detailEnantioseparation of nonsteroidal anti-inflammatory drugs by capillary electrophoresis using mixtures of anionic and uncharged beta-cyclodextrins as chiral additives.
Fillet, Marianne ULg; Hubert, Philippe ULg; Crommen, Jacques ULg

in Electrophoresis (1997), 18(6), 1013-8

Nine nonsteroidal anti-inflammatory drugs (NSAIDs) were enantioseparated by capillary electrophoresis using an anionic cyclodextrin derivative (sulfobutyl ether beta-cyclodextrin or carboxymethyl-beta ... [more ▼]

Nine nonsteroidal anti-inflammatory drugs (NSAIDs) were enantioseparated by capillary electrophoresis using an anionic cyclodextrin derivative (sulfobutyl ether beta-cyclodextrin or carboxymethyl-beta-cyclodextrin) in combination with a neutral cyclodextrin as chiral additives to a pH 3 phosphoric acid-triethanolamine buffer. In the presence of a negatively charged cyclodextrin, the analytes were given an appropriate mobility but relatively low enantioselectivities were generally obtained when such a cyclodextrin was the only selector added to the buffer. The addition of an uncharged cyclodextrin, such as the native beta-cyclodextrin or one of its derivatives (dimethyl-, trimethyl- and hydroxypropyl-beta-cyclodextrin), to this kind of buffer containing an anionic cyclodextrin, was found to give rise to considerable improvement in chiral resolution for all compounds studied. Resolution and analysis time were optimized by varying the nature and concentration of the two cyclodextrins. The best compromise was usually achieved by the simultaneous addition of sulfobutyl ether beta-cyclodextrin and trimethyl-beta-cyclodextrin. Under optimum conditions, the enantiomers of all NSAIDs examined could be completely separated (most often with resolution values higher than 5) in short analysis times (generally lower than 15 min). [less ▲]

Detailed reference viewed: 23 (5 ULg)
Peer Reviewed
See detailEnantioseparations in non-aqueous capillary electrophoresis (NACE)
Crommen, Jacques ULg; Rousseau, Anne; Fradi, Ines et al

Conference (2011)

Detailed reference viewed: 5 (0 ULg)
Full Text
See detailEnantioseparations in nonaqueous capillary electrophoresis using charged cyclodextrins.
Servais, Anne-Catherine ULg; Fillet, Marianne ULg

in Methods in Molecular Biology 970: Chiral Separations (2013)

The enantioseparation of acidic and basic compounds can be successfully achieved in nonaqueous capillary electrophoresis using single-isomer charged beta-cyclodextrin (beta-CD) derivatives of opposite ... [more ▼]

The enantioseparation of acidic and basic compounds can be successfully achieved in nonaqueous capillary electrophoresis using single-isomer charged beta-cyclodextrin (beta-CD) derivatives of opposite charge to that of the analytes. This chapter describes how to separate the enantiomers of three basic substances selected as model compounds, i.e., alprenolol, bupranolol, and terbutaline, using the negatively charged heptakis(2,3-di-O-acetyl-6-O-sulfo)-beta-CD. The enantiomers of three acidic drugs (tiaprofenic acid, suprofen, and flurbiprofen) are resolved using a monosubstituted amino beta-CD derivative, namely, 6-monodeoxy-6-mono(3-hydroxy)propylamino-beta-CD. [less ▲]

Detailed reference viewed: 13 (2 ULg)
See detailEncadrement : mythes ou réalités !
Boxus, Elise; Hanzen, Christian ULg; Horward, Jean-Luc ULg et al

Report (1994)

Résultats de l'enquête menée en 1992 auprès des membres des corps académique et scientifique de l'Université de Liège.

Detailed reference viewed: 50 (9 ULg)