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enantiomer separation

Goutam Ghosh, Sarah J Belh, Callistus Chiemezie, Niluksha Walalawela, Ashwini A Ghogare, Mariana Vignoni, Andrés H Thomas, Sherri A McFarland, Edyta M Greer, Alexander Greer
There is a major need for light-activated materials for the release of sensitizers and drugs. Considering the success of chiral columns for the separation of enantiomer drugs, we synthesized an S,S-chiral linker system covalently attached to silica with a sensitizer ethene near the silica surface. First, the silica surface was modified to be aromatic rich, by replacing 70% of the surface groups with (3-phenoxypropyl)silane. We then synthesized a 3-component conjugate [chlorin sensitizer, S,S-chiral cyclohexane, and ethene building blocks] in 5 steps with a 13% yield, and covalently bound the conjugate to the (3-phenoxypropyl)silane-coated silica surface...
August 16, 2018: Photochemistry and Photobiology
Chiharu Ishii, Takeyuki Akita, Masashi Mita, Tomomi Ide, Kenji Hamase
An automated two-dimensional HPLC-MS/MS system was designed and developed for the highly selective determination of trace levels of d-amino acids. As the targets, frequently observed ones in mammalian physiological fluids, Ala, Asp, Glu, Leu, Pro and Ser, were selected because these d-amino acids are the potential biomarkers for the early and sensitive diagnoses of various diseases. The target analytes were derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F), then isolated by a reversed-phase column in the first dimension...
July 29, 2018: Journal of Chromatography. A
Lia Bezhitashvili, Anna Bardavelidze, Antonina Mskhiladze, Mehmet Gumustas, Sibel A Ozkan, Alessandro Volonterio, Tivadar Farkas, Bezhan Chankvetadze
Our earlier studies have demonstrated the applicability of polysaccharide-based chiral selectors in combination with superficially porous (or core-shell) silica (SPS) particles for the preparation of highly efficient chiral stationary phases (CSP). In earlier studies, CSPs were prepared by coating (adsorption) of the chiral selector onto the surface of silica. In this study we report for the first time the CSP obtained by covalent immobilization of a chiral selector onto the surface of SPS particles. The applicability of this CSP for the separation of enantiomers in pure methanol and acetonitrile, as well as in n-hexane/2-propanol mobile phases is shown...
August 4, 2018: Journal of Chromatography. A
Liqiong Lv, Huawei Lv, Xujun Qiu, Jizhong Yan, Shengqiang Tong
Racemic trans-paroxol, trans-N-methylparoxetine and trans-paroxetine containing two chiral centres were stereoselectively separated using countercurrent chromatography with hydroxypropyl-β-cyclodextrin as the chiral selector. A two-phase solvent system composed of n-butyl acetate and 0.1 mol L-1 sodium carbonate-sodium bicarbonate buffer at pH 9.2 (1:1, v/v) was selected, and 0.10 mol L-1 hydroxypropyl-β-cyclodextrin was added to the aqueous phase as the chiral selector. Racemic trans-N-methylparoxetine and racemic trans-paroxol (20 mg of each) were stereoselectively separated by countercurrent chromatography in an individual run, yielding 7...
July 27, 2018: Journal of Chromatography. A
Cemil Aydoğan
A novel chiral porous-layer stationary phase was developed for use in open-tubular nano liquid chromatography. The stationary phase was prepared by an in-situ polymerization of 3-chloro-2-hydroxypropylmethacrylate (HPMA-Cl) and ethylene dimethacrylate (EDMA). The reactive chloro groups at the surface of the porous stationary phase were reacted with β-Cyclodextrin (β-CD). The resulting morphology was characterized by using scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FT-IR)...
August 10, 2018: Chirality
Yilun Yan, Jun Fan, Dong Guo, Yuemei Lin, Yecai Lai, Tai Wang, Hao Gao, Xinsheng Yao, Weiguang Zhang
Semi-preparative separation of lenalidomide has been performed through supercritical fluid chromatography. In regard to retention and resolution of lenalidomide, effects of chromatographic conditions, such as chiral stationary phases, organic co-solvents, mobile phases, and column temperature, have been studied in detail. Amylose tris(3, 5-dimethylphenylcarbamate)-coated and the single-urea-bound β-cyclodextrin chiral stationary phases exhibited good separation performances for lenalidomide in the CO2 -methanol mixture...
August 10, 2018: Journal of Separation Science
Ann Gogolashvili, Elene Tatunashvili, Lali Chankvetadze, Tamas Sohajda, Julianna Szeman, Mehmet Gumustas, Sibel A Ozkan, Antonio Salgado, Bezhan Chankvetadze
The affinity pattern of terbutaline enantiomers towards various cyclodextrins was studied using capillary electrophoresis. The affinity pattern of terbutaline enantiomers was the same towards all studied cyclodextrins except heptakis(2-O-methyl-3,6-di-O-sulfo)-β-CD. Nuclear magnetic resonance spectroscopy was used for understanding of fine structural mechanisms of interactions of β-cyclodextrin and its two sulfated derivatives with the enantiomers of terbutaline. The structure of terbutaline complexes with all 3 cyclodextrins studied was different from each other...
August 4, 2018: Journal of Chromatography. A
Amanda E Kotheimer, Wahajul Haq, Ganesaratnam K Balendiran
Practical synthetic route for the formation of enantiomeric mixture of Isopropyl 2-(4-((4-chlorophenyl)(hydroxyl)methyl)phenoxy)-2-methylpropanoate (Fibratol 2a/b) from isopropyl 2-(4-(4-chlorobenzoyl)phenoxy)-2-methylpropanoate (Fenofibrate 1) has been developed. Method has also been established for the chiral separation of enantiomers of Fibratol 2a/b that is synthesized using the route mentioned above. The optical activity determined for enantiomerically separated Fibratol (2a) and Fibratol (2b) are -5.2° and 8...
June 2018: International Journal of Organic Chemistry
Sergey P Verevkin, Vladimir N Emel'yanenko, Andrey A Pimerzin, Andrei V Yermalayeu
This work is a contribution to the molecular understanding of the thermodynamic properties of the chiral compounds. A comprehensive thermochemical study of the liquid enantiopure and racemate pairs of optically active alkyl lactates has been performed. Vapor pressures of DL-(±)-, L-(-)-methyl-, and DL-(±)-, L-(-)-n-butyl esters of lactic acid were measured by the transpiration method. The liquid phase standard molar enthalpies of formation of these esters were measured by using the high-precision combustion calorimetry...
August 7, 2018: Journal of Chemical Physics
Mohie M K Sharaf El-Din, Khalid A M Attia, Mohamed W I Nassar, Mohamed M Y Kaddah
In this study, the chromatographic conditions for separation and determination of L- and D-lactic acid enantiomers by copper ligand exchange chromatography have been examined and optimized statistically using a response surface methodology (RSM). The chromatographic variables: copper sulfate, acetic acid and organic modifier were screened by operating a 2-level full factorial design (FFD). The significant effect of independent chromatographic variables was analyzed using the analysis of variance (ANOVA). Variables proved significant (p < 0...
November 1, 2018: Talanta
Judyta Hejniak, Irena Baranowska, Sandra Stencel, Sylwia Bajkacz
A study of the simultaneous separation and determination of selected polyphenols (rutin, narirutin, naringin, hesperidin, neohesperidin, quercetin, naringenin, kaempferol and hesperetin) with reported effects in the treatment of depression and cardiac and neurodegenerative diseases was performed. An RP-ultrahigh-performance liquid chromatography (UHPLC)-ultraviolet method for analyte separation and determination was successfully developed and validated for a ZORBAX Eclipse Plus C18 RRHD analytical column. Separation was carried out in gradient elution mode with acetonitrile and water modified with 0...
July 31, 2018: Journal of Chromatographic Science
Haibing Li, Jiaxin Quan, Guanrong Nie, Hong Xue, Li Luo, Ruiping Zhang
Chiral recognition as an intrinsic process of life, plays a crucial role in chemical systems, and further forms various architectures in the resulted functional materials. So far, relevant studies were focused on the recognition of chiral molecules. However, the weak chiral interaction transformed into macroscopic recognition such as chiral drug droplets is much more crucial due to its applicability in controlling the drugs selective delivery and convenient for drugs enantiomer separation. In this report, chiral calix[4]arene was introduced onto the surface to chiral recognition of S-naproxen droplet through host-guest interaction...
August 3, 2018: Chemistry: a European Journal
Soheila Chalavi, Ali Reza Fakhari, Saeed Nojavan
In this study, a chiral CE method was developed based on the partial filling technique with two chiral plugs for the simultaneous enantioseparation of some racemic drugs, including baclofen, carvedilol, cetirizine, chlorpheniramine, citalopram, fluoxetine, hydroxyzine, propranolol, tramadol, trihexyphenidyl. This method of capillary filling involves the application of two adjacent chiral plugs containing the same BGE, but with different chiral selectors in the plugs for the enantioseparation of a mixture of drugs which cannot be separated with single or mixed chiral selectors...
September 14, 2018: Journal of Chromatography. A
Shawn T Phillips, James N Dodds, Berkley M Ellis, Jody C May, John A McLean
In this study ion mobility-mass spectrometry (IM-MS) is used to distinguish chiral diastereomers of the nonapeptides desmopressin and vasopressin. The differences in gas phase cross sectional area (ca. 2%) were sufficient to directly resolve the enantiomers present in a binary mixture. Results from computational modeling indicate that chiral recognition by IM-MS for nonapeptides is possible due to their diastereomer-specific conformations adopted in the gas-phase, namely a compact ring-tail conformer specific to the l-diastereomer forms...
July 31, 2018: Chemical Communications: Chem Comm
Lucia Guillade, Federica Sarno, Hanna Tarhnskaya, Angela Nebbioso, Susana Alvarez, Akane Kawamura, Christopher Schofield, Lucia Altucci, Angel R de Lera
The natural product tripartin has been reported to inhibit the N-methyl lysine histone demethylase KDM4A. A synthesis of tripartin starting from 3,5-dimethoxyphenylacrylic acid was developed and the enantiomers were separated by chiral HPLC. We observed that both tripartin enantiomers manifested an apparent increase in the H3K9me3 levels when dosed in cells, as measured by Western blot analysis. Thus, there is no enantiomeric discrimination towards this natural product in terms of its effects on cellular histone methylation status...
July 26, 2018: ChemMedChem
Blanka R Szulc, Stephen T Hilton, Arnaud J Ruiz
We have synthesized a novel small molecule based on the pyrrolidinone-containing core structure of clausenamide, which is a candidate anti-dementia drug. The synthetic route yielded multi-gram quantities of an isomeric racemate mixture in a short number of steps. When tested in hippocampal slices from young adult rats the compound enhanced AMPA receptor-mediated signalling at mossy fibre synapses, and potentiated inward currents evoked by local application of l-glutamate onto CA3 pyramidal neurons. It facilitated the induction of mossy fibre LTP, but the magnitude of potentiation was smaller than that observed in untreated slices...
July 22, 2018: Molecular and Cellular Neurosciences
Xuan Yang, Zhi Yan, Tao Yu, Yingxiang Du, Jiaquan Chen, Zongran Liu, Ying Xi
Several chiral reagents including cyclodextrins (CDs) and derivatives, crown ethers, proteins, chiral surfactants, and polymers have been involved in dual-selector systems for enantioseparation of a series of compounds by capillary electrophoresis (CE). In this paper, chondroitin sulfate D-based dual-selector system (CSD/CM-β-CD) was firstly established and investigated for the enantioseparation of six basic racemic drugs in capillary electrophoresis. Compared to the single-selector systems, synergistic effect and significantly improved separations for all tested analytes were observed in CSD/CM-β-CD system...
July 24, 2018: Analytical and Bioanalytical Chemistry
Peter P Lankhorst, Jozef H J van Rijn, Alexander L L Duchateau
The discrimination of enantiomers of mandelonitrile by means of 1D 13 C NMR and with the aid of the chiral solvating agent (S)-(+)-1-(9-anthryl)-2,2,2-trifluoroethanol (TFAE) is presented. ¹H NMR fails for this specific compound because proton signals either overlap with the signals of the chiral solvating agent or do not show separation between the (S)-enantiomer and the (R)-enantiomer. The 13 C NMR method is validated by preparing artificial mixtures of the (R)-enantiomer and the racemate, and it is shown that with only 4 mg of mandelonitrile a detection limit of the minor enantiomer of 0...
July 20, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Fengxiang Qie, Jiahui Guo, Bin Tu, Xing Zhao, Yuchun Zhang, Yong Yan
Efficient resolution of racemic mixture has long been the most attractive but challenging subject since Pasteur separated tartrate enantiomers in 19th century. Graphene oxide (GO) could be flexibly functionalized by using a variety of chiral host molecules and therefore, was expected to show excellent enantioselective resolution performance. However, this combination with efficient enantioselective resolution capability has been scarcely demonstrated. Here, Nanopores graphene oxides were firstly produced and then covalently functionalized by using a chiral host material-β-cyclodextrin (β-CD)...
July 23, 2018: Chemistry, An Asian Journal
Linda Luo, Xiaoli Wen, Yueying Du, Zhen Jiang, Xingjie Guo
A highly rapid, sensitive and enantioselective method was developed and fully validated for the separation and determination of lansoprazole enantiomers in rat plasma by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The analytes and the internal standard (esomeprazole) were both extracted from plasma samples by liquid-liquid extraction with diethyl ether-dichloromethane (70:30; v/v). Satisfactory resolution (Rs = 2.0) was achieved within 7.3 min on a Chiralpak ID column (250 mm×4.6 mm, 5 μm) employing acetonitrile-water (60:40, v/v) as the mobile phase at a flow rate of 0...
July 20, 2018: Biomedical Chromatography: BMC
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