keyword
MENU ▼
Read by QxMD icon Read
search

Chiral separation

keyword
https://www.readbyqxmd.com/read/29140426/development-and-validation-of-stereo-selective-method-for-the-separation-of-razoxane-enantiomers-in-hydrophilic-interaction-chromatography
#1
Ch Thirupathi, K Nagesh Kumar, G Srinivasu, Ch Lakshmi Narayana, Ch Parameswara Murthy
A novel sensitive and high throughput chiral hydrophilic interaction chromatographic (HILIC) method was developed to separate razoxane enantiomers namely levrazoxane (R-isomer) and dexrazoxane (DEX) in pharmaceutical active ingredient samples. A systematic chiral chromatographic screening system was employed in using multiple HPLC chromatographic modes on various polysaccharide based chiral columns to obtain a potential separation between enantiomers. HPLC separation was achieved using a mobile phase of aqueous 10 mM ammonium bicarbonate and mixture of organic modifiers (70/30, v/v) in the ratio of (5/95, v/v) on an immobilized polysaccharide based chiral stationary phase namely CHIRALPAK IE-3...
November 13, 2017: Journal of Chromatographic Science
https://www.readbyqxmd.com/read/29136927/enantioselective-determination-of-metconazole-in-multi-matrices-by-high-performance-liquid-chromatography
#2
Rujian He, Jun Fan, Qi Tan, Yecai Lai, Xiaodong Chen, Tai Wang, Ying Jiang, Yaomou Zhang, Weiguang Zhang
A reliable and effective HPLC analytical method has been developed to stereoselectively quantify metconazole in soil and flour matrices. Effects of polysaccharide chiral stationary phase, type and content of alcoholic modifier on separation of racemic metconazole have been discussed in detail. Resolution and quantitative determination of metconazole stereoisomers were performed by using an Enantiopak OD column, with the n-hexane-ethanol mixture (97:3, v/v) at the flow rate of 1.0mL/min. Then, extraction and cleanup procedures followed by the modified QuEChERS (quick, easy, cheap, effective, rugged and safe) method were used for metconazole racemate in soil and flour matrices...
February 1, 2018: Talanta
https://www.readbyqxmd.com/read/29136083/differentiation-of-enantiomeric-anions-by-nmr-spectroscopy-with-chiral-bisurea-receptors
#3
Suguru Ito, Manami Okuno, Masatoshi Asami
Chiral anionic species are ubiquitous and play important roles in biological systems. Despite the recent advancements in synthetic anion receptors bearing urea functionalities, urea-based chiral solvating agents (CSAs) that can separate the NMR signals of racemic anions remain limited. Herein, three dibenzofuran-based C2-symmetric chiral bisureas were synthesized from the reaction of (R,R)-4,6-bis(1-aminopropyl)dibenzo[b,d]furan with phenyl isocyanate, phenyl thioisocyanate, or tosyl isocyanate. The chiral anion recognition properties of these bisureas were examined by (1)H NMR spectroscopy using dl-tetrabutylammonium mandelate (TBAM) as a model substrate...
November 14, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/29133815/lc-ms-guided-isolation-of-three-pairs-of-enantiomeric-alkaloids-from-macleaya-cordata-and-their-enantioseparations-antiproliferative-activity-apoptosis-inducing-property
#4
Chunmei Sai, Dahong Li, Shengge Li, Tong Han, Yongzhi Guo, Zhanlin Li, Huiming Hua
(±)-Macleayins F-H (1-3), three pairs of new enantiomeric alkaloid dimers, along with four known alkaloids (4-7) as their plausible biogenetic precursors, were isolated from the aerial parts of Macleaya cordata. Compounds 1-3 were obtained under the guidance of LC-MS investigation, and their structures were elucidated by analysis of the 1D and 2D NMR spectroscopic data. The racemic mixtures were successfully separated by chiral HPLC, and the absolute configurations of enantiomers were determined by electronic circular dichroism (ECD) spectroscopy...
November 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29131945/enantioselectivity-of-2-2-3-5-6-pentachlorobiphenyl-pcb-95-atropisomers-toward-ryanodine-receptors-ryrs-and-their-influences-on-hippocampal-neuronal-networks
#5
Wei Feng, Jing Zheng, Gaelle Robin, Yao Dong, Makoto Ichikawa, Yoshihisa Inoue, Tadashi Mori, Takeshi Nakano, Isaac N Pessah
Nineteen ortho-substituted PCBs are chiral and found enantioselectively enriched in ecosystems. Their differential actions on biological targets are not understood. PCB 95 (2,2',3,5',6-pentachlorobiphenyl), a chiral PCB of current environmental relevance, is among the most potent towards modifying ryanodine receptors (RyR) function and Ca2+ signaling. PCB 95 atropisomers are separated and assigned aR- and aS-PCB 95 using 3 chiral-columns HPLC and circular dichroism spectroscopy. Studies of RyR1-enriched microsomes show aR-PCB 95 with >4X greater potency (EC50=0...
November 13, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/29126741/design-synthesis-and-biological-evaluation-of-hydantoin-bridged-analogues-of-combretastatin-a-4-as-potential-anticancer-agents
#6
Mao Zhang, Yu-Ru Liang, Huan Li, Ming-Ming Liu, Yang Wang
A series of novel hydantoin-bridged analogues of combretastatin A-4 (CA-4) were designed, synthesized and evaluated for antiproliferative activities in vitro and in vivo. The most potent compound 8d, showed potent cytotoxicity against four human cancer cell lines with IC50 values of 0.186-0.279 μM, and possessed the efficacy of inhibiting tubulin polymerization, disrupting in vitro vascularization, blocking cell cycle in G2/M phase and inducing cell apoptosis. In the nude mice xenograft model, 8d significantly inhibited the tumor growth and showed low toxicity...
November 1, 2017: Bioorganic & Medicinal Chemistry
https://www.readbyqxmd.com/read/29126076/a-rapid-and-sensitive-chiral-lc-ms-ms-method-for-the-determination-of-ketamine-and-norketamine-in-mouse-plasma-brain-and-cerebrospinal-fluid-applicable-to-the-stereoselective-pharmacokinetic-study-of-ketamine
#7
Hidetoh Toki, Takuya Ichikawa, Akiko Mizuno-Yasuhira, Jun-Ichi Yamaguchi
A novel method for the rapid and sensitive chiral determination of ketamine and norketamine in mouse plasma, brain and cerebrospinal fluid (CSF) was developed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). This method reduces the required matrix volume, compared with a previously reported chiral assay method for ketamine and norketamine. The method involves the deproteinization of a small amount of biological matrix (corresponding to 5μL of plasma, 10mg of brain, or 2.5μL of CSF) using a water-miscible organic solvent containing (2)H4-norketamine as an internal standard, the direct injection of the organic supernatant into an LC-MS/MS system, chiral separation on a CHIRALPAK AS-3R column (4...
October 7, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/29100613/density-dependence-of-retention-factors-of-trans-stilbene-oxide-for-chiral-separation-by-supercritical-fluid-chromatography
#8
Toshitaka Funazukuri, Yuna Ono, Junichi Sakabe, Chang Yi Kong
Retention factors for two enantiomers of trans-stilbene oxide, k1 and k2, were measured with a chiral AD-H column using two syringe pumps to feed CO2 and methanol as a co-solvent at various temperatures, pressures and co-solvent mole fractions to determine the effects of these operating conditions on the retention factors. The retention factors k1 and k2 are for the (R,R)- and (S,S)-forms, respectively. When the isothermal compressibilities of a mixture of CO2 and MeOH were lower than 0.01, far from the critical locus of the CO2 and methanol mixture, both retention factors were well expressed with the solvent density and temperature with an average absolute relative deviation of 1-2%...
October 28, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/29092400/synthesis-of-chiral-tritylpyrrolidine-derivatives-and-their-application-to-asymmetric-benzoyloxylation
#9
Mio Shimogaki, Hiroki Maruyama, Shingo Tsuji, Chihiro Homma, Taichi Kano, Keiji Maruoka
An efficient synthesis of novel chiral tritylpyrrolidine derivatives has been developed. Single stereoisomers of various tritylpyrrolidine derivatives can be readily obtained through diastereomer separation by simple silica gel column chromatography. Representative compounds of this class have been shown to be efficient amine organocatalysts for asymmetric benzoyloxylation.
November 13, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29080267/synthesis-of-new-c3-symmetric-amino-acid-and-aminoalcohol-containing-chiral-stationary-phases-and-application-to-hplc-enantioseparations
#10
Jeongjae Yu, Daniel W Armstrong, Jae Jeong Ryoo
We recently reported a new C3-symmetric (R)-phenylglycinol N-1,3,5-benzenetricarboxylic acid-derived chiral high-performance liquid chromatography (HPLC) stationary phase (CSP 1) that demonstrated better results as compared to a previously described N-3,5-dintrobenzoyl (DNB) (R)-phenylglycinol-derived CSP. Over a decade ago, (S)-leucinol, (R)-phenylglycine, and (S)-leucine derivatives were used as the starting materials of 3,5-DNB-based Pirkle-type CSPs for chiral separation. In this study, three new C3-symmetric CSPs (CSP 2, 3, and 4) were prepared by combining the ideas and results mentioned above...
October 28, 2017: Chirality
https://www.readbyqxmd.com/read/29072720/cannabis-through-the-looking-glass-chemo-and-enantio-selective-separation-of-phytocannabinoids-by-enantioselective-ultra-high-performance-supercritical-fluid-chromatography
#11
G Mazzoccanti, O H Ismail, I D'Acquarica, C Villani, C Manzo, M Wilcox, A Cavazzini, F Gasparrini
By using the Inverted Chirality Columns Approach (ICCA) we have developed an enantioselective UHPSFC method to determine the enantiomeric excess (ee) of (-)-Δ(9)-THC in medicinal marijuana (Bedrocan®). The ee was high (99.73%), but the concentration of the (+)-enantiomer (0.135%) was not negligible, and it is worth a systematic evaluation of bioactivity.
October 26, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/29067704/separation-of-chiral-compounds-using-magnetic-molecularly-imprinted-polymer-nanoparticles-as-stationary-phase-by-microchip-capillary-electrochromatography
#12
Lu-Lu Wu, Ru-Ping Liang, Juan Chen, Jian-Ding Qiu
In this work, a simple and rapid approach was developed for separation and detection of chiral compounds based on a magnetic molecularly imprinted polymer modified poly(dimethylsiloxane) (PDMS) microchip coupled with electrochemical detection. Molecularly imprinted polymers were prepared employing Fe3 O4 nanoparticles (NPs) as the supporting substrate and norepinephrine as the functional monomer in the presence of template molecule in a weak alkaline solution. After extracting the embedded template molecules, Fe3 O4 @polynorepinephrine NPs (MIP-Fe3 O4 @PNE NPs) showed specific molecular recognition selectivity and high affinity towards the template molecule, which were then used as stationary phase of microchip capillary electrochromatography for chiral compounds separation...
October 25, 2017: Electrophoresis
https://www.readbyqxmd.com/read/29064670/pair-of-stereodynamic-chiral-benzylicaldehyde-probes-for-determination-of-absolute-configuration-of-amino-acid-residues-in-peptides-by-mass-spectrometry
#13
Lin Wang, Zhe Jin, Xiayan Wang, Su Zeng, Cuirong Sun, Yuanjiang Pan
This paper describes a simple method to determine the absolute configuration of amino acids residues in peptides by mass spectrometry using a newly developed pair of mass-tagged chiral probes without the requirement of reference standards. A pair of benzylicaldehyde probes, 1-(S)-(1)H in S configuration and 2-(R)-(2)D in deuterium-labeled R configuration with the ratio of 1:1, were synthesized for in situ condensation with amino acid residues and transformed into a pair of stereodynamic imine products. The characteristic intensity difference observed in mass spectrometry can be used to determine the absolute configuration and to quantify the enantiomeric composition of chiral amino acid residues...
November 7, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/29064231/chiral-measurement-of-aspartate-and-glutamate-in-single-neurons-by-large-volume-sample-stacking-capillary-electrophoresis
#14
Amit V Patel, Takayuki Kawai, Liping Wang, Stanislav S Rubakhin, Jonathan V Sweedler
d-Amino acids (d-AAs) are endogenous molecules found throughout the metazoan, the functions of which remain poorly understood. Measurements of low abundance and heterogeneously distributed d-AAs in complex biological samples, such as cells and multicellular structures of the central nervous system (CNS), require the implementation of sensitive and selective analytical approaches. In order to measure the d- and l-forms of aspartate and glutamate, we developed and applied a stacking chiral capillary electrophoresis (CE) with laser-induced fluorescence detection method...
November 8, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/29059613/capillary-electrophoresis-separation-of-phenethylamine-enantiomers-using-amino-acid-based-ionic-liquids
#15
Joachim Wahl, Ulrike Holzgrabe
In recent years increasing interest was drawn towards ionic liquids in analytical separation science, such as capillary electrophoresis. Ionic liquids combining tetrabutylammonium cations with chiral amino acid based anions were prepared and investigated as capillary electrophoresis background electrolyte additives for the enantioseparation of ephedrine, pseudoephedrine, and methylephedrine isomers. For the optimization of buffer pH and ionic liquid concentration a design of experiments approach was performed...
October 17, 2017: Journal of Pharmaceutical and Biomedical Analysis
https://www.readbyqxmd.com/read/29056780/asymmetric-solution-phase-mixture-aldol-reaction-using-oligomeric-ethylene-glycol-tagged-chiral-oxazolidinones
#16
Serhan Turkyilmaz, Craig S Wilcox
Sorting tags are oligomeric structures that can be used as protecting groups or chiral auxiliaries enabling solution-phase mixture syntheses of multiple tagged compounds in one pot and allowing for facile and predictable chromatographic separation of products at the end of synthetic sequences. Perfluorinated hydrocarbon and oligomeric ethylene glycol (OEG) derivatives are known classes of sorting tags. Herein we describe the preparation of OEGylated chiral oxazolidinones and their use in asymmetric solution-phase mixture aldol reactions...
May 24, 2017: Tetrahedron Letters
https://www.readbyqxmd.com/read/29053274/from-racemic-metal-nanoparticles-to-optically-pure-enantiomers-in-one-pot
#17
Huayan Yang, Juanzhu Yan, Yu Wang, Guocheng Deng, Haifeng Su, Xiaojing Zhao, Chaofa Xu, Boon K Teo, Nanfeng Zheng
A general strategy, using mixed ligands, is utilized to synthesize atomically precise, intrinsically chiral nanocluster [Ag78(DPPP)6(SR)42] (Ag78) where DPPP is the achiral 1,3-bis(diphenyphosphino)propane and SR = SPhCF3. Ag78 crystallizes as racemates in a centric space group. Using chiral diphosphines BDPP = 2,4-bis(diphenylphosphino)pentane, the enantiomeric pair [Ag78(R/S-BDPP)6(SR)42] can be prepared with 100% optical purity. The chiral diphosphines gives rise to, separately, two asymmetric surface coordination motifs composed of tetrahedral R3PAg(SR)3 moieties...
November 7, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29048847/-preparation-of-filter-paper-with-chiral-separation-function-by-oxidation-and-schiff-base-reaction
#18
Lixin Luo, Xinghua Zhao, Minjie Jiang, Haiyan Zhang, Yu Wang
Paper chromatography (PC) is a highly flexible, fast, and efficient separation method. In this study, a chromatographic paper with a chiral separation function was investigated and a paper chromatographic method for chiral separation was developed. Single-factor experiments and orthogonal tests were used to determine the optimal oxidation conditions for filter paper. The optimal conditions were that sodium periodate 4% (mass percentage), pH 2 buffer solution, reaction temperature 45℃, and reaction time 4 h...
September 8, 2017: Se Pu, Chinese Journal of Chromatography
https://www.readbyqxmd.com/read/29048834/-preparation-and-performance-characterization-of-gold-nanoparticles-modified-chiral-capillary-electrochromatography-stationary-phase
#19
Lele Xiong, Ruijun Li, Yibing Ji
Gold nanoparticles (GNPs, 15 nm) were prepared and introduced to amino groups derived silica monolithic column. Bovine serum albumin (BSA) was immobilized via covalent modification method onto the carboxylic functionalized GNPs to afford chiral stationary phase (CSP) for enantioseparation. GNPs were well dispersed and successfully incorporated onto the columns with the contents as high as 17.18% by characterization method such as transmission electron microscopy (TEM), ultraviolet (UV)-visible absorption spectra and scanning electron microscopy (SEM)...
July 8, 2017: Se Pu, Chinese Journal of Chromatography
https://www.readbyqxmd.com/read/29048833/-new-c2-symmetric-chiral-stationary-phases-based-on-l-proline-derivatives-as-chains
#20
Long Chen, Lingping Cheng, Shanshan He, Yunchao He, Yaling Wu, Yanxiong Ke, Xinmiao Liang
C2 symmetric chiral compounds overlap themselves when rotating with an axis of 180° with an axis and have important applications in chiral catalysis and chiral separation fields. A novel C2 symmetric stationary phase based on phenyl substituted L-proline derivatives was prepared and compared with the similar stationary phase based on mono-substituted brush-type stationary phase. The C2 symmetric stationary phase showed higher enantiodiscrimination capability than the mono-substituted stationary phase for 31 acidic, neutral and alkaline analytes...
July 8, 2017: Se Pu, Chinese Journal of Chromatography
keyword
keyword
87410
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"