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Chiral separation

Zoltán-István Szabó, Réka Gál, Levente Szőcs, Róbert Ludmerczki, Daniela-Lucia Muntean, Béla Noszál, Gergő Tóth
The enantiomers of praziquantel, the drug of choice in schistosomiasis, were separated by electrokinetic chromatography with cyclodextrins. Nine anionic cyclodextrins were screened for their ability to discriminate between the uncharged enantiomers. Seven investigated selectors presented chiral interactions with the enantiomers, these cases being interpreted in terms of stability constants and complex mobilities. The best results were delivered by sulfated-β-cyclodextrin, where quasi-equal stability constants were accompanied by extreme selectivity values and was explained on the basis of highly different mobilities of the transient diastereomeric complexes...
February 21, 2017: Electrophoresis
Nuria Menéndez-López, Jesús Valimaña-Traverso, María Castro-Puyana, Antonio Salgado, María Ángeles García, María Luisa Marina
Two analytical methodologies were developed by CE enabling the enantiomeric separation of colchicine, an antiuremic drug commercialized as pure enantiomer. Succinyl-γ-CD and Sulfated-γ-CD were selected as chiral selectors after a screening with different anionic CDs. Under the optimized conditions, chiral resolutions of 5.6 in 12min and 3.2 in 8min were obtained for colchicine with Succinyl-γ-CD and Sulfated-γ-CD, respectively. An opposite enantiomeric migration order was observed with these two CDs being S-colchicine the first-migrating enantiomer with Succinyl-γ-CD and the second-migrating enantiomer with Sulfated-γ-CD...
February 2, 2017: Journal of Pharmaceutical and Biomedical Analysis
Hiroki Segawa, Yuko T Iwata, Tadashi Yamamuro, Kenji Kuwayama, Kenji Tsujikawa, Tatsuyuki Kanamori, Hiroyuki Inoue
The enantiomers of methamphetamine were differentiated by supercritical fluid chromatography (SFC) with an enantioselective cellulose-based packed column. The optimization of the chromatographic conditions was achieved by changing column temperature, co-solvent proportion, additive concentration, flow rate and back pressure. In particular, the additive concentration crucially changed the resolution between the enantiomers. After determining the optimized conditions, the enantiomers of methamphetamine were successfully separated...
February 4, 2017: Forensic Science International
Lu Zheng, Chengyuan Yu, Yulin Zhan, Xuebing Deng, Ying Wang, Hua Jiang
A series of foldamers of 8-amino-2-quinolinecarboxylic acid were stapled by intramolecular ring-closing olefin metathesis to generate the constrained aromatic foldamers with varying lengths of hydrocarbon side-chains. Investigations clearly revealed that the side-chain crosslinkers are capable of completely locking the interconversions of the stapled aromatic foldamers over a wide range of temperature in CDCl3, even in C2D2Cl4. Hence, the stapled foldamers with the short hydrocarbon crosslinker can be easily separated by silica gel chromatography to generate foldamers with stable, absolute one-handed helicity...
February 16, 2017: Chemistry: a European Journal
Chadin Kulsing, Yuanzhong Yang, Jamil M Chowdhury, Reinhard I Boysen, Milton T W Hearn
This investigation demonstrates the application of a new peak sharpening technique to improve the separation of difficult-to-resolve racemic mixtures in capillary electro-chromatography. Molecularly imprinted porous layer open tubular (MIP-PLOT) capillaries, prepared by a layer-on-layer polymerization approach with Z-l-Asp-OH as the template, were selected to validate the approach. SEM revealed that the polymer film thickness can be varied by changes in both the polymer composition and the layer-on-layer regime...
February 17, 2017: Electrophoresis
Andrea Carotti, Federica Ianni, Emidio Camaioni, Lucia Pucciarini, Maura Marinozzi, Roccaldo Sardella, Benedetto Natalini
In search for new enantioselectivity profiles, the N-decyl-S-trityl-(R)-cysteine [C10-(R)-STC] was synthesized through a one-step procedure and then hydrophobically adsorbed onto an octadecylsilica surface to generate a stable chiral stationary phase for ligand-exchange chromatography (CLEC-CSP) applications. The CLEC analysis was carried out on underivatized amino acids, by using a Cu(II) sulphate (1.0mM) containing aqueous eluent system. Most of the analysed compounds (34 out of 45) were enantiodiscriminated by the C10-(R)-STC-based CSP, with resolution factor (RS) values up to 8...
February 5, 2017: Journal of Pharmaceutical and Biomedical Analysis
Mariana Silva, Damián Pérez-Quintanilla, Sonia Morante-Zarcero, Isabel Sierra, María Luisa Marina, Zeineb Aturki, Salvatore Fanali
In this paper a chiral stationary phase (CSP) was prepared by the immobilization of a β-CD derivative (3,5-dimethylphenylcarbamoylated β-CD) onto the surface of amino-functionalized spherical ordered mesoporous silica (denoted as SM) via a urea linkage using the Staudinger reaction. The CSP was packed into fused silica capillaries 100μm I.D. and evaluated by means of nano-liquid chromatography (nano-LC) and capillary electrochromatography (CEC) using model compounds for the enantio- and the diastereomeric separation...
February 9, 2017: Journal of Chromatography. A
Chandan L Barhate, Erik L Regalado, Nathan D Contrella, Joon Lee, Junyong Jo, Alexey A Makarov, Daniel W Armstrong, Christopher J Welch
Chromatographic separation and analysis of complex mixtures of closely related species is one of the most challenging tasks in modern pharmaceutical analysis. In recent years, two-dimensional liquid chromatography (2D-LC) has become a valuable tool for improving peak capacity and selectivity. However, the relatively slow speed of chiral separations has limited the use of chiral stationary phases (CSPs) as the second dimension in 2D-LC, especially in the comprehensive mode. Realizing that the recent revolution in the field of ultrafast enantioselective chromatography could now provide significantly faster separations, we herein report an investigation into the use of ultrafast chiral chromatography as a second dimension for 2D chromatographic separations...
January 23, 2017: Analytical Chemistry
Sys Stybe Johansen
Citalopram is one of the most frequently used antidepressants in Denmark. Citalopram is marketed as a racemic mixture (50:50) of S- and R-enantiomers as well as of the S-enantiomer alone, which is the active enantiomer named escitalopram that processes the inhibitory effects. In this study, a chiral liquid chromatography-tandem mass spectrometry (LC-MS/MS) method is developed for the measurement of citalopram and demethylcitalopram enantiomers in whole blood and is applied to forensic cases. Whole blood samples (0...
February 8, 2017: Drug Testing and Analysis
Bo Yang, Jie Zhou, Yong Wang, Jian Tang, Weihua Tang
The enantioseparations of 12 isoxazoline racemates were explored with four perphenylcarbamate cyclodextrin (CD) clicked chiral stationary phases (CSPs) in high performance liquid chromatography (HPLC). The results demonstrated that the functionalities on phenylcarbamate moiety greatly determined the chiral separation ability of CD clicked CSPs. Among of them, per(3-chloro-4-methylphenylcarbamate) CD clicked CSP (CCC3M4-CSP) exhibited the best enantioseparation ability, affording 4ClPh-OPr with a chiral resolution over 20 in ternary eluent mobile phases...
February 8, 2017: Electrophoresis
Bolin Zhu, Shuying Xu, Xingjie Guo, Lan Wei, Jia Yu, Tiejie Wang
A capillary electrophoretic method for the enantioseparation of ofloxacin and its five related substances (potential impurities, indicated as impurities B, C, D, E, and F) was developed using β-cyclodextrin derivatives as chiral selectors. To our knowledge, there are no previous studies about using capillary electrophoresis for the separation of impurities B, C, and D. Six β-cyclodextrin derivatives including cationic (piperidine- and cyclohexylamine-), neutral (dimethyl- and hydroxypropyl-) and anionic (carboxymethyl- and sulfated-) β-cyclodextrin derivatives were tested and operational parameters such as buffer pH and concentration of β-cyclodextrin derivatives were investigated...
February 7, 2017: Journal of Separation Science
Paola Peluso, Victor Mamane, Emmanuel Aubert, Sergio Cossu
The term Atropisomerism defines a type of enantiomerism that arises from hindered rotation around an axis that makes two rotational isomers enantiomers. Atropisomeric compounds are present in nature, being important building blocks of many biologically active compounds. Atropisomers have been extensively studied in environmental and toxicological chemistry and, in particular, separating them has become a need in specific fields as organic synthesis and pharmaceutical research. High-performance liquid chromatography has been fruitfully applied in this context, and, despite HPLC separation on chiral stationary phase (CSP) is considered as mature technology nowadays, in the last years several advancements and applications contributed to study compounds where axial chirality is of utmost importance...
February 6, 2017: Electrophoresis
Ju-Yen Fu, Thet-Thet Htar, Leanne De Silva, Doryn Meam-Yee Tan, Lay-Hong Chuah
Vitamin E is recognized as an essential vitamin since its discovery in 1922. Most vegetable oils contain a mixture of tocopherols and tocotrienols in the vitamin E composition. Structurally, tocopherols and tocotrienols share a similar chromanol ring and a side chain at the C-2 position. Owing to the three chiral centers in tocopherols, they can appear as eight different stereoisomers. Plant sources of tocopherol are naturally occurring in the form of RRR while synthetic tocopherols are usually in the form of all-racemic mixture...
February 4, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Oleg A Levitskiy, Yuri K Grishin, Olesya O Semivrazhskaya, Asmik A Ambartsumyan, Konstantin A Kochetkov, Tatiana V Magdesieva
Stereoselective electrosynthesis of the first individual ((f,t) A)- and ((f,t) C)-1,4-fullerene derivatives with a non-inherently chiral functionalization pattern is described, as well as the first example of an optically pure protected primary amino acid directly linked to the fullerene through only the chiral α-amino-acid carbon atom. An application of an auxiliary chiral nickel-Schiff base moiety as derivatizing agent allowed separation of ((f,t) A)- and ((f,t) C)-1,4-fullerene derivatives using an achiral stationary phase, a separation which has never been done before...
March 1, 2017: Angewandte Chemie
Carlos Calderón, Michael Lämmerhofer
Chiral short chain aliphatic hydrocarboxylic acids (HCAs) are common compounds being part of different biological processes. In order to control and understand these processes is of pivotal importance to determine the identity of the involved enantiomer or their enantiomeric ratio. In this study the capacity of quinine- and quinidine-derived chiral stationary phases to perform the enantioseparation of eight chiral HCAs (tartaric acid, isocitric acid, malic acid, glyceric acid, 2-hydroxyglutaric acid, 2-hydroxybutyric acid, lactic acid and 3-hydroxybutyric acid) was evaluated...
March 3, 2017: Journal of Chromatography. A
Terézia Vojtylová, Věra Hamplová, Zbigniew Galewski, Izabela Korbecka, David Sýkora
Chiral high-performance liquid chromatography separation of two recently synthesized liquid crystalline materials C1 and C2 was studied in the reversed-phase mode. Both materials have an azo-moiety and one chiral centre in their molecular structures. They were available in racemic and pure S forms. For the enantiomeric separations, a Chiralpak AY-RH stationary phase based on amylose tris(5-chloro-2-methylphenylcarbamate) coated on 5 μm silica was used. The compounds were analyzed in both of their possible forms, the more thermodynamically stable E form and the labile Z form...
January 31, 2017: Journal of Separation Science
Benedetta Pasquini, Fabrizio Melani, Claudia Caprini, Massimo Del Bubba, Sergio Pinzauti, Serena Orlandini, Sandra Furlanetto
A comprehensive investigation on the CE separation mechanisms and on the inclusion complexation with CyDs of the chiral drug S-ambrisentan (S-AMB), its R-enantiomer and other impurities was performed by different techniques. A CE method was previously set up allowing the simultaneous determination of the enantiomeric purity and of impurities of S-AMB, based on the addition of SDS micelles and γ-cyclodextrin (γCyD) to borate buffer. In this study, the electrophoretic behavior of the analytes in terms of selectivity and mobility with respect to the addition of different CyDs was first investigated, evidencing the presence of interactions for all the CyDs, but the unique ability of γCyD for obtaining the separation of all the compounds...
January 21, 2017: Journal of Pharmaceutical and Biomedical Analysis
Joachim Wahl, Takayuki Furuishi, Etsuo Yonemochi, Lorenz Meinel, Ulrike Holzgrabe
To optimize chiral separation conditions and to improve the knowledge of enantioseparation it is important to know the binding constants K between analytes and cyclodextrins and the electrophoretic mobilities of the temporarily formed analyte-cyclodextrin-complexes. K values for complexes between 8 phenethylamine enantiomers, namely ephedrine, pseudoephedrine, methylephedrine and norephedrine, and 4 different β-cyclodextrin derivatives were determined by affinity capillary electrophoresis. The binding constants were calculated from the electrophoretic mobility values of the phenethylamine enantiomers at increasing concentrations of cyclodextrins in running buffer...
January 28, 2017: Electrophoresis
Xuyi Yue, Hongjun Jin, Zonghua Luo, Hui Liu, Xiang Zhang, Ethan D McSpadden, Linlin Tian, Hubert P Flores, Joel S Perlmutter, Stanley M Parsons, Zhude Tu
Twelve optically pure enantiomers were obtained using either crystallization or chiral high performance liquid chromatography (HPLC) separation methodologies to resolve six racemic sigma-1 (σ1) receptor ligands. The in vitro binding affinities of each enantiomer for σ1, σ2 receptors and vesicular acetylcholine transporter (VAChT) were determined. Out of the 12 optically pure enantiomers, five displayed very high affinities for σ1 (Ki<2nM) and high selectivity for σ1 versus σ2 and VAChT (>100-fold)...
February 15, 2017: Bioorganic & Medicinal Chemistry
Jacob J Terracina, Susan T Sharfstein, Magnus Bergkvist
A 2-step molecular mechanical and quantum mechanical geometry optimization scheme (MM ➔ QM) was used to "computationally imprint" chiral molecules. Using a docking technique, we show the imprinted binding sites to exhibit an enantioselective preference for the imprinted molecule over its enantiomer. Docking of structurally similar chiral molecules showed that the sites computationally imprinted with R- or S-tBOC-tyrosine were able to differentiate between R- and S-forms of other tyrosine derivatives. The cross-enantioselectivity did not hold for chiral molecules that did not share the tyrosine H-bonding functional group orientations...
January 25, 2017: Journal of Molecular Recognition: JMR
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