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Chirality

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https://www.readbyqxmd.com/read/27901292/differential-in-radiosensitizing-potency-of-enantiomers-of-the-fatty-acid-synthase-inhibitor-c75
#1
Colin Rae, John W Babich, Robert J Mairs
The elevated activity of fatty acid synthase has been reported in a number of cancer types. Inhibition of this enzyme has been demonstrated to induce cancer cell death and reduce tumor growth. In addition, the fatty acid synthase inhibitor drug C75 has been reported to synergistically enhance the cancer-killing ability of ionizing radiation. However, clinical use of C75 has been limited due to its producing weight loss, believed to be caused by alterations in the activity of carnitine palmitoyltransferase-1...
November 30, 2016: Chirality
https://www.readbyqxmd.com/read/27862337/effects-of-solvent-on-inclusion-complexation-of-a-chiral-dipeptide-toward-racemic-binol
#2
Xiaoyun Hu, Yuyuan Yang, Shuai Shi, Zixing Shan
The effects of reaction solvent on inclusion complexation of a chiral dipeptide (3S,6S)-1 derived from (S)-proline toward racemic BINOL was investigated, discovering that the reaction solvent played a crucial role in determining the inclusion complexation behavior of dipeptide (3S,6S)-1 toward rac-BINOL. (3S,6S)-1 did not show any chiroselective or achiroselective complexation toward rac-BINOL in polar protic solvents such as methanol and ethanol, polar aprotic solvents including trichloromethane and THF, while in polar aprotic solvent ethyl acetate and apolar aprotic solvents benzene, (3S,6S)-1 displayed achiroselective complexation toward rac-BINOL...
November 16, 2016: Chirality
https://www.readbyqxmd.com/read/27862348/enantioselective-effects-of-metalaxyl-on-soil-enzyme-activity
#3
Heng Yue, Song Fang, Yizhi Zhang, Yang Ning, Weisong Yu, Fanyu Kong, Jun Qiu
The enantioselective effects of the chiral pesticide metalaxyl on soil enzyme activity were investigated. Incubation experiments were conducted to investigate the effects of metalaxyl enantiomers at different concentrations on the activities of urease, invertase, and catalase as well as the type of activity change (activation vs. inhibition) at different times during incubation. The results indicated that the effects of metalaxyl on the activity of soil enzymes were not only related to the concentration of the enantiomers and soil incubation time, but also to the chiral configuration, suggesting the effects were enantioselective...
November 10, 2016: Chirality
https://www.readbyqxmd.com/read/27897331/a-convenient-and-validated-enantiomer-separation-of-chiral-aliphatic-amines-as-nitrobenzoxadiazole-derivatives-on-polysaccharide-derived-chiral-stationary-phases-under-simultaneous-ultraviolet-and-fluorescence-detection
#4
Suraj Adhikari, Jong Seong Kang, Wonjae Lee
A convenient method using a fluorogenic agent, 4-chloro-7-nitro-1,2,3-benzoxadiazole (NBD-Cl), was developed for enantiomer separation of chiral aliphatic amines including amino alcohols by normal high-performance liquid chromatography. The enantiomer separation of chiral aliphatic amines as NBD derivatives was performed on six covalently bonded and four coated-type polysaccharide-derived chiral stationary phases (CSPs) under simultaneous ultraviolet (UV) and fluorescence detection (FLD). Among the covalently bonded CSPs, Chiralpak IE showed the best enantiomer separation for most analytes...
December 2016: Chirality
https://www.readbyqxmd.com/read/27897330/bernard-l-feringa-nobel-prize-for-chemistry-2016
#5
EDITORIAL
David B Amabilino, Nina D Berova, John Caldwell
No abstract text is available yet for this article.
December 2016: Chirality
https://www.readbyqxmd.com/read/27897329/molecules-in-molecules-fragment-based-method-for-the-calculation-of-chiroptical-spectra-of-large-molecules-vibrational-circular-dichroism-and-raman-optical-activity-spectra-of-alanine-polypeptides
#6
K V Jovan Jose, Krishnan Raghavachari
The molecules-in-molecules (MIM) fragment-based method has recently been adapted to evaluate the chiroptical (vibrational circular dichroism [VCD] and Raman optical activity [ROA]) spectra of large molecules such as peptides. In the MIM-VCD and MIM-ROA methods, the relevant higher energy derivatives of the parent molecule are assembled from the corresponding derivatives of smaller fragment subsystems. In addition, the missing long-range interfragment interactions are accounted at a computationally less expensive level of theory (MIM2)...
December 2016: Chirality
https://www.readbyqxmd.com/read/27897328/solid-phase-extraction-with-metal-organic-frameworks-for-the-analysis-of-chiral-compounds
#7
Bo Tang, Jun-Hui Zhang, Min Zi, Xue-Xian Chen, Li-Ming Yuan
Metal-organic frameworks (MOFs) are excellent porous materials with nanoscale cavities and high surface areas, which make them promising as novel adsorbents in solid-phase extraction (SPE). In this article we report a new application of the chiral MOF [Zn2 (D-Cam)2 (4,4'-bpy)]n in SPE used for the measurement of the enantiomeric excess (ee) of (±)-1,1'-bi-2-naphthol. Several important experimental parameters that may influence the extraction efficiency were investigated and optimized. Under the optimum conditions, a good linearity (R(2)  > 0...
December 2016: Chirality
https://www.readbyqxmd.com/read/27897327/high-performance-liquid-chromatography-evaluation-of-the-enantiomeric-purity-of-amino-acids-by-means-of-automated-precolumn-derivatization-with-ortho-phthalaldehyde-and-chiral-thiols
#8
Raphael Kühnreich, Ulrike Holzgrabe
The use of ortho-phthalaldehyde (OPA) for the derivatization of amino acids (AA) is well known. It enables the separation of the derivatives on common reversed phase columns and improves the sensitivity with fluorescence detection. With the use of a chiral thiol an indirect enantioseparation of chiral amines and AAs is feasible. The major drawback of the OPA-derivatization is the poor stability of the products. Here, a method with an in-needle derivatization procedure is optimized to facilitate a quantitative conversion of the AA with OPA and the chiral thiols N-acetyl-L-cysteine or N-isobutyryl-L-cysteine, followed by a subsequent analysis, eluding the stability issue...
December 2016: Chirality
https://www.readbyqxmd.com/read/27791320/claisen-schmidt-condensation-synthesis-of-1s-6r-1r-6s-2-oxo-n-4-6-triarylcyclohex-3-enecarboxamide-derivatives-with-different-substituents-in-h2-o-etoh
#9
Seyyed Rasul Mousavi
A simple, green, and direct three-component condensation of acetophenone, aromatic aldehydes with 3-oxo-N-phenylbutanamide (acetoacetanilide) to generate some novel (1S,6R)/(1R,6S)-2-oxo-N,4,6-triarylcyclohex-3-enecarboxamide derivatives was carried out over K2 CO3 (10 mol%) with high efficiency in water/ethanol as green solvent at room temperature. This protocol proceeded via Claisen-Schmidt condensation and Michael addition. The present methodology offers several advantages, such as short reaction time, high yield, more readily available and inexpensive materials, more environmentally friendly, no need for column chromatography, simple work-up procedure, and the absence of volatile and hazardous organic solvents...
November 2016: Chirality
https://www.readbyqxmd.com/read/27791319/analysis-of-flumequine-enantiomers-in-rat-plasma-by-uflc-esi-ms-ms
#10
Zhao-Hong Hu, Yang-Guang Wang, Huo-Xi Jin, Xiao-Kun Ouyang, Wei-Jian Wu
In this study the analysis and confirmation of flumequine enantiomers in rat plasma by ultra-fast liquid chromatography coupled with electron spray ionization mass spectrometry (using propranolol as an internal standard [IS]) was developed and validated. Plasma samples were prepared by liquid-liquid extraction using methyl tert-butyl ether as the extraction solvent. Direct resolution of the R- and S-isomers was performed on a CHIRALCEL OJ-RH column (4.6 × 150 mm, 5 μm) using acetonitrile / 0.1% formic acid / 1 mM ammonium acetate as the mobile phase...
November 2016: Chirality
https://www.readbyqxmd.com/read/27791318/highly-enantioselective-michael-addition-of-cyclohexanone-to-nitroolefins-catalyzed-by-pyrrolidine-based-bifunctional-benzoylthiourea-in-water
#11
Zhen-Yu Wang, Shu-Rong Ban, Meng-Chen Yang, Qing-Shan Li
Organocatalysis and aqueous reactions are identified as the focus of the greening of chemistry. Combining these two strategies effectively remains an interesting challenge in organic synthesis. Herein, we used pyrrolidine-based benzoylthiourea 1c to catalyze the asymmetric Michael addition of cyclohexanone to various nitroolefins in water to afford the corresponding compounds in moderate to good yields, and with excellent diastereoselectivities (up to >99:1 dr) and enantioselectivities (up to 99% ee).
November 2016: Chirality
https://www.readbyqxmd.com/read/27791317/a-stereodynamic-phosphoramidite-ligand-derived-from-3-3-functionalized-ortho-biphenol-and-its-rhodium-i-complex
#12
Golo Storch, Luisa Deberle, Jan-Michael Menke, Frank Rominger, Oliver Trapp
Stereodynamic ligands and complexes bearing functional groups to attach chiral or achiral binding sites and auxiliaries are highly attractive due to the interesting opportunities for controlling the stereochemical outcome of enantioselective transformations. In this study we report the preparation of a 3,3'-functionalized biphenol (BIPOL) phosphoramidite ligand (PAm ) bearing 3,5-dichlorobenzoyl (3,5-DCB) amide binding sites for noncovalent interactions. Upon coordination to [Rh(COD)2 ]BF4 this substitution pattern directs one of the 3,5-DCB binding sites in close proximity of the metal center resulting in liberation of both COD ligands and the formation of a [Rh(PAm )2 ]BF4 complex...
November 2016: Chirality
https://www.readbyqxmd.com/read/27791316/diastereomeric-bactericidal-effect-of-ru-phenanthroline-2-dipyridophenazine
#13
Anna K F Mårtensson, Mattias Bergentall, Valentina Tremaroli, Per Lincoln
Metal susceptibility assays and spot plating were used to investigate the antimicrobial activity of enantiopure [Ru(phen)2 dppz](2+) (phen =1,10-phenanthroline and dppz = dipyrido[3,2-a:2´,3´-c]phenazine) and [μ-bidppz(phen)4 Ru2 ](4)(+) (bidppz =11,11´-bis(dipyrido[3,2-a:2´,3´-c]phenazinyl)), on Gram-negative Escherichia coli and Gram-positive Bacillus subtilis as bacterial models. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) were determined for both complexes: while [μ-bidppz(phen)4 Ru2 ](4)(+) only showed a bactericidal effect at the highest concentrations tested, the antimicrobial activity of [Ru(phen)2 dppz](2+) against B...
November 2016: Chirality
https://www.readbyqxmd.com/read/27791315/good-computational-practice-in-the-assignment-of-absolute-configurations-by-tddft-calculations-of-ecd-spectra
#14
(no author information available yet)
No abstract text is available yet for this article.
November 2016: Chirality
https://www.readbyqxmd.com/read/27670249/circularly-polarized-luminescence-a-review-of-experimental-and-theoretical-aspects
#15
REVIEW
Giovanna Longhi, Ettore Castiglioni, Jun Koshoubu, Giuseppe Mazzeo, Sergio Abbate
We review the present status of experiments and calculations for circularly polarized luminescence (CPL) of simple organic molecules and of stimuli-responsive organic molecules. Together with the historical report of the main instrumental approaches, a few crucial points about experiments are tackled, with the aim of defining measurement protocols, in view of the wide availability of commercial apparatuses in the near future. The calculations aimed at interpreting the CPL spectra, mostly based on time-dependent Density Functional Theory (TD-DFT) calculations, which started around 2010, are reviewed, limiting the discussion to small to mid-sized molecules...
October 2016: Chirality
https://www.readbyqxmd.com/read/27670248/discrimination-of-axial-and-central-stereogenic-elements-in-chiral-bis-oxazolines-based-on-atropisomeric-3-3-bithiophene-scaffolds-through-chiroptical-spectroscopies
#16
Sara Gabrieli, Giuseppe Mazzeo, Giovanna Longhi, Sergio Abbate, Tiziana Benincori
Two diastereoisomeric pairs of bis-oxazolines, provided with a stereogenic center at carbon 4 and based on the 3,3'-bithiophene atropisomeric scaffold, were synthesized and structurally characterized. They differ in the substituents at positions 2 and 5 of the thiophene rings, which are functionalized with methyl (1) or phenyl (2) groups, respectively. In vibrational circular dichroism (VCD) spectra, recorded in CCl4 solutions, it is possible to distinctly recognize the characteristic features of axial and central stereogenic elements...
October 2016: Chirality
https://www.readbyqxmd.com/read/27612650/editors-note-chirality-in-separation-science-and-molecular-recognition-honoring-prof-f-gasparrini-thematic-issue-2016
#17
EDITORIAL
Claudio Villani
No abstract text is available yet for this article.
October 2016: Chirality
https://www.readbyqxmd.com/read/27581600/structural-basis-and-mechanism-of-chiral-benzedrine-molecules-interacting-with-third-dopamine-receptor
#18
Ming Wang, Wei Xie, Aijing Li, Sichuan Xu
In order to investigate the chiral benzedrine molecules corresponding to their different characteristics in biochemical systems, we studied their interaction with D3 R using the docking method, molecular dynamic simulation, and quantum chemistry. The obtained results indicate that the active residues for R-benzedrine (RAT) bound with D3 R are Ala132, Asp133, and Tyr55, while Asn57, Asp133, Asp168, Cys172, Gly54, Trp24, and Vall136 act as the active residues for S-benzedrine (SAT). The different active pockets are observed for ART or SAT because they possess different active residues...
October 2016: Chirality
https://www.readbyqxmd.com/read/27581384/preparation-of-enantiomerically-pure-s-1-1-naphthyl-ethanol-by-the-fungus-alternaria-alternata
#19
Kani Zilbeyaz, Esabi Basaran Kurbanoglu, Hamdullah Kilic
(S)-(-)-1-(1'-napthyl)-ethanol (S-NE) is an important intermediate for the preparation of mevinic acid analogs, which is used for the treatment of hyperlipidemia. The objectives of the study were to isolate a microorganism that could effectively reduce 1-acetonaphthone (1-ACN) to S-NE, to determine the influence that the physicochemical parameters would have on the reduction by the isolated microorganism, and to attempt large-scale studies with the microorganism. Over the years fungi have been considered a promising biocatalyst and it has been presumed that many fungal species have not been isolated and therefore the current study focused on possible isolation of these microorganisms...
October 2016: Chirality
https://www.readbyqxmd.com/read/27563754/chiroptical-properties-of-streptorubin-b-the-synergy-between-theory-and-experiment
#20
(no author information available yet)
No abstract text is available yet for this article.
September 2016: Chirality
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