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https://www.readbyqxmd.com/read/28032028/easily-accessible-thermotropic-hydrogen-bonded-columnar-discotic-liquid-crystals-from-fatty-acid-tris-benzoimidazolyl-benzene-complexes
#1
Jody A M Lugger, Rint P Sijbesma
We report the formation of easily accessible hydrogen-bonded columnar discotic liquid crystals (LCs) based on tris-benzoimidazolyl benzene (TBIB) and commercially available fatty acids. By increasing the length of the fatty acid, the temperature range of liquid crystallinity was tuned. Introducing double bonds in octadecanoic acid lowered the crystallization temperature and increased the temperature range of the mesophase. Surprisingly, dimerized linoleic acid also forms an LC phase. When using branched aliphatic acids with the branching point close to the acid moiety, the mesophase was lost, whereas phosphonic acid or benzenesulfonic acid derivatives did have a mesophase, showing that the generality of this approach extends beyond carboxylic acids as the hydrogen-bond donor...
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/28032027/valosin-containing-protein-is-a-target-of-5-l-fuligocandin%C3%A2-b-and-enhances-trail-resistance-in-cancer-cells
#2
Midori A Arai, Shota Taguchi, Kazuhiro Komatsuzaki, Kento Uchiyama, Ayaka Masuda, Mana Sampei, Mamoru Satoh, Sayaka Kado, Masami Ishibashi
Fuligocandin B (2) is a novel natural product that can overcome TRAIL resistance. We synthesized enatiomerically pure fuligocandin B (2) and its derivative 5'-I fuligocandin B (4), and found that the latter had an improved biological activity against the human gastric cancer cell line, AGS. We attached a biotin linker and photoactivatable aryl diazirine group to 5'-I fuligocandin B (4), and employed a pull-down assay to identify valosin-containing protein (VCP/p97), an AAA ATPase, as a 5'-I fuligocandin B (4) target protein...
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/28032026/synthesis-of-11-c-labeled-sulfonyl-carbamates-through-a-multicomponent-reaction-employing-sulfonyl-azides-alcohols-and-11-c-co
#3
Marc Y Stevens, Shiao Y Chow, Sergio Estrada, Jonas Eriksson, Veronika Asplund, Anna Orlova, Bogdan Mitran, Gunnar Antoni, Mats Larhed, Ola Åberg, Luke R Odell
We describe the development of a new methodology focusing on (11)C-labeling of sulfonyl carbamates in a multicomponent reaction comprised of a sulfonyl azide, an alkyl alcohol, and [(11)C]CO. A number of (11)C-labeled sulfonyl carbamates were synthesized and isolated, and the developed methodology was then applied in the preparation of a biologically active molecule. The target compound was obtained in 24±10 % isolated radiochemical yield and was evaluated for binding properties in a tumor cell assay; in vivo biodistribution and imaging studies were also performed...
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/28032025/syntheses-structures-and-complexation-studies-of-tris-organostannyl-methane-derivatives
#4
Anicet Siakam Wendji, Michael Lutter, Lukas M Stratmann, Klaus Jurkschat
The syntheses of tris(organostannyl)methanes HC(SnX n Ph(3-n))3 (1, n=0; 2, n=1, X=I; 3, n=1, X =F; 4, n=1, X=Cl; 5, n=1, X=OAc; 6, n=2, X=I; 7, n=2, X=Cl) and the organostannate complexes Et4N[HC(SnIPh2)3⋅F] (8), Ph4P[HC(SnClPh2)3⋅Cl] (9), and [Ph4P]2[HC(SnCl2Ph)3⋅2 Cl] (10) are reported. The compounds were characterized by (1)H, (13)C, (19)F, and (119)Sn NMR spectroscopy, IR spectroscopy, electrospray mass spectrometry, and (with the exception of 3) single-crystal X-ray diffraction analysis...
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/28032024/urinary-measurement-of-epigenetic-dna-modifications-a-non-invasive-assessment-of-the-whole-body-epigenetic-status-in-healthy-subjects-and-colorectal-cancer-patients
#5
Rafal Rozalski, Daniel Gackowski, Agnieszka Siomek-Gorecka, Zbigniew Banaszkiewicz, Ryszard Olinski
Active mechanism of DNA demethylation can be responsible for the activation of previously silenced genes. Products of 5-methylcytosine oxidation are released into the bloodstream and eventually excreted with urine. Therefore, whole-body epigenetic status can be assessed non-invasively on the basis of the urinary excretion of a broad spectrum of epigenetic modifications: 5-hydroxymethylcytosine (5-hmCyt), 5-formylcytosine (5-fCyt), 5-carboxycytosine (5-caCyt), and 5-hydroxymethyluracil (5-hmUra). We have developed a specific and sensitive, isotope-dilution, automated, online, two-dimensional ultra-performance liquid chromatography system with tandem mass spectrometry (2D UPLC-MS/MS) to measure 5-hmCyt, 5-fCyt, 5-caCyt, and their deoxynucleosides in the same urine sample...
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/28032023/chiral-br%C3%A3-nsted-acid-catalyzed-enantioselective-%C3%AE-amidoalkylation-reactions-a-joint-experimental-and-predictive-study
#6
Eider Aranzamendi, Sonia Arrasate, Nuria Sotomayor, Humberto González-Díaz, Esther Lete
Enamides with a free NH group have been evaluated as nucleophiles in chiral Brønsted acid-catalyzed enantioselective α-amidoalkylation reactions of bicyclic hydroxylactams for the generation of quaternary stereocenters. A quantitative structure-reactivity relationship (QSRR) method has been developed to find a useful tool to rationalize the enantioselectivity in this and related processes and to orient the catalyst choice. This correlative perturbation theory (PT)-QSRR approach has been used to predict the effect of the structure of the substrate, nucleophile, and catalyst, as well as the experimental conditions, on the enantioselectivity...
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/28032022/direct-assembly-of-prenylated-heteroarenes-through-a-cascade-minisci-reaction-dehydration-sequence
#7
Dong-Hang Tan, Yao-Fu Zeng, Yao Liu, Wen-Xin Lv, Qingjiang Li, Honggen Wang
The prenyl group is an important component in bioactive compounds. Herein, we report the assembly of prenylated heteroarenes through a cascade Minisci reaction and acid-promoted dehydration sequence. The use of potassium (3-hydroxy-3-methylbut-1-yl)trifluoroborate as a new coupling reagent allows the direct introduction of prenyl and 3-hydroxy-3-methylbutyl groups to a wide variety of electron-deficient heteroarenes. Synthetic application is also demonstrated.
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/28032021/detection-of-ligand-induced-conformational-changes-in-the-activation-loop-of-aurora-a-kinase-by-peldor-spectroscopy
#8
Selena G Burgess, Maria Grazia Concilio, Richard Bayliss, Alistair J Fielding
The structure of protein kinases has been extensively studied by protein crystallography. Conformational movement of the kinase activation loop is thought to be crucial for regulation of activity; however, in many cases the position of the activation loop in solution is unknown. Protein kinases are an important class of therapeutic target and kinase inhibitors are classified by their effect on the activation loop. Here, we report the use of pulsed electron double resonance (PELDOR) and site-directed spin labeling to monitor conformational changes through the insertion of MTSL [S-(1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1 H-pyrrol-3-yl)methyl methanesulfonothioate] on the dynamic activation loop and a stable site on the outer surface of the enzyme...
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/28032020/facile-preparation-of-chloride-conducting-membranes-first-step-towards-a-room-temperature-solid-state-chloride-ion-battery
#9
Fabienne Gschwind, Dominik Steinle, Daniel Sandbeck, Celine Schmidt, Elizabeth von Hauff
Three types of chloride-conducting membranes based on polyvinyl chloride, commercial gelatin, and polyvinyldifluoride-hexafluoropolymer are introduced in this report. The polymers are mixed with chloride-containing salts, such as tetrabutylammonium chloride, and cast to form membranes. We studied the structural properties, thermal stability, and electrochemical response of the membranes to understand chloride migration and transport. Finally, the membranes are tested in a prototype solid-state chloride-ion battery setup...
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/28032019/lewis-acid-assisted-hydrogen-atom-transfer-to-manganese-v-oxo-corrole-through-valence-tautomerization
#10
Curt J Bougher, Mahdi M Abu-Omar
The kinetics of formation of the valence tautomers (tpfc(⋅))Mn(IV)(O-LA)] (n+) [where LA=Zn(II), Ca(II), Sc(III), Yb(III), B(C6F5)3, and trifluoroacetic acid (TFA); tpfc=5,10,15-tris(pentafluorophenyl) corrole] from (tpfc)Mn(V)(O) were followed by UV/Vis spectroscopy, giving second-order rate constants ranging over five orders of magnitude from 10(-2) for Ca to 10(3)  m (-1) s(-1) for Sc. Hydrogen atom transfer (HAT) rates from 2,4-di-tert-butyl phenol (2,4-DTBP) to the various Lewis acid valence tautomers of manganese oxo corrole complexes were evaluated and compared...
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/28032018/a-multi-target-small-molecule-for-targeted-transcriptional-activation-of-therapeutically-significant-nervous-system-genes
#11
Yulei Wei, Ganesh N Pandian, Tingting Zou, Junichi Taniguchi, Shinsuke Sato, Gengo Kashiwazaki, Thangavel Vaijayanthi, Takuya Hidaka, Toshikazu Bando, Hiroshi Sugiyama
An integrated multi-target small molecule capable of altering dynamic epigenetic and transcription programs associated with the brain and nervous system has versatile applications in the regulation of therapeutic and cell-fate genes. Recently, we have been constructing targeted epigenetic ON switches by integrating sequence-specific DNA binding pyrrole-imidazole polyamides with a potent histone deacetylase inhibitor SAHA. Here, we identified a DNA-based epigenetic ON switch termed SAHA-L as the first-ever multi-target small molecule capable of inducing transcription programs associated with the human neural system and brain synapses networks in BJ human foreskin fibroblasts and 201B7-iPS cells...
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/28032017/the-power-of-biocatalysis-a-one-pot-total-synthesis-of-rhamnolipids-from-butane-as-the-sole-carbon-and-energy-source
#12
Christian Gehring, Mirja Wessel, Steffen Schaffer, Oliver Thum
Microbially derived surfactants, so-called biosurfactants, have drawn much attention in recent years and are expected to replace current petrochemical surfactants, owing to their environmental and toxicological benefits. One strategy to support that goal is to reduce production costs by replacing relatively expensive sugars with cheaper raw materials, such as short-chain alkanes. Herein, we report the successful one-pot total synthesis of rhamnolipids, a class of biosurfactants with 12 stereocenters, from butane as sole carbon and energy source through the design of a tailored whole-cell biocatalyst...
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/28032016/rapid-naked-eye-discrimination-of-cytochrome-p450-genetic-polymorphism-through-non-crosslinking-aggregation-of-dna-functionalized-gold-nanoparticles
#13
Yoshitsugu Akiyama, Guoqing Wang, Shota Shiraishi, Naoki Kanayama, Tohru Takarada, Mizuo Maeda
Involvement of single-nucleotide polymorphism (SNP) genotyping in healthcare should allow for more effective use of pharmacogenomics. However, user-friendly assays without the requirement of a special instrument still remain unavailable. This study describes naked-eye SNP discrimination in exon 5 of the human cytochrome P450 2C19 monooxygenase gene, CYP2C19*1 (the wild-type allele) and CYP2C19*2 (the variant allele with G681A point mutation). The present assay is composed of allele-specific single-base primer extension and salt-induced aggregation of DNA-modified gold nanoparticles (DNA-AuNPs)...
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/28032015/rapid-naked-eye-discrimination-of-cytochrome-p450-genetic-polymorphism-through-non-crosslinking-aggregation-of-dna-functionalized-gold-nanoparticles
#14
Yoshitsugu Akiyama, Guoqing Wang, Shota Shiraishi, Naoki Kanayama, Tohru Takarada, Mizuo Maeda
The front cover artwork is provided by the group of Tohru Takarada at RIKEN (Japan). The image shows a colorimetric single-nucleotide polymorphism (SNP) genotyping method that uses spontaneous aggregation of DNA-modified gold nanoparticles (DNA-AuNPs) for the simple and rapid SNP genotyping of the human cytochrome P450 2C19 monooxygenase gene. For more details, read the full text of the Full Paper at p. 508.
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/28032014/cover-picture-rapid-naked-eye-discrimination-of-cytochrome-p450-genetic-polymorphism-through-non-crosslinking-aggregation-of-dna-functionalized-gold-nanoparticles-chemistryopen-6-2016
#15
Yoshitsugu Akiyama, Guoqing Wang, Shota Shiraishi, Naoki Kanayama, Tohru Takarada, Mizuo Maeda
The Front Cover picture shows a colorimetric single-nucleotide polymorphism (SNP) genotyping method using spontaneous aggregation of DNA-modified gold nanoparticles (DNA-AuNPs). Simple and rapid SNP genotyping of the human cytochrome P450 2C19 monooxygenase gene is reported. Allele-specific single-base primer extension using a fragment of the gene isolated from human hair roots, followed by salt-induced aggregation of DNA-AuNPs, results in a rapid color change from red to blue or no color change, thereby allowing SNP discrimination by the naked eye...
December 2016: ChemistryOpen
https://www.readbyqxmd.com/read/27777844/back-cover-induction-of-an-infinite-periodic-minimal-surface-by-endowing-an-amphiphilic-zwitterion-with-halogen-bond-ability-chemistryopen-5-2016
#16
Takahiro Ichikawa, Akiyoshi Okafuji, Takashi Kato, Hiroyuki Ohno
The Back Cover picture illustrates the attachment of iodine atoms onto the headgroup of an amphiphilic zwitterion, which leads to the formation of a bicontinuous cubic liquid-crystalline assembly with a primitive-type infinite periodic minimal surface. More information can be found in the Communication by T. Ichikawa, H. Ohno and co-workers on page 439 in Issue 5, 2016 (DOI: 10.1002/open.201600054).
October 2016: ChemistryOpen
https://www.readbyqxmd.com/read/27777843/catalytic-degradation-of-benzene-over-nanocatalysts-containing-cerium-and-manganese
#17
Zhen Wang, Yuzhou Deng, Genli Shen, Sadia Akram, Ning Han, Yunfa Chen, Qi Wang
A Ce-Mn composite oxide possessing a rod-like morphology (with a fixed molar ratio of Ce/Mn=3:7) was synthesized through a hydrothermal method. Mn ions were doped into a CeO2 framework to replace Ce ions, thereby increasing the concentration of oxygen vacancies. The formation energies of O vacancies for the Ce-Mn composite oxide were calculated by applying density functional theory (DFT). The data showed that it was easier to form an O vacancy in the composite. The catalytic behavior of the Ce-Mn composite oxide for benzene degradation was researched in detail, which exhibited a higher activity than the pure phases...
October 2016: ChemistryOpen
https://www.readbyqxmd.com/read/27777842/regioselective-synthesis-of-a-family-of-%C3%AE-lactams-bearing-a-triazole-moiety-as-potential-apoptosis-inhibitors
#18
Maria Garrido, Miriam Corredor, Mar Orzáez, Ignacio Alfonso, Angel Messeguer
Apoptosis is a biological process important to several human diseases; it is strongly regulated through protein-protein interactions and complex formation. We previously reported the synthesis of apoptosis inhibitors bearing an exocyclic triazole amide isoster by using an Ugi four-component coupling reaction (Ugi-4CC), followed by a base-promoted intramolecular cyclization. Depending on the substitution patterns and the reaction conditions, this cyclization forms the six- or four-membered ring. Two compounds bearing the β-lactam scaffold turned out to be the most potent inhibitors...
October 2016: ChemistryOpen
https://www.readbyqxmd.com/read/27777841/synthesis-of-a-new-series-of-sialylated-homo-and-heterovalent-glycoclusters-by-using-orthogonal-ligations
#19
Gour Chand Daskhan, Carlo Pifferi, Olivier Renaudet
The synthesis of heteroglycoclusters (hGCs) is being subjected to rising interest, owing to their potential applications in glycobiology. In this paper, we report an efficient and straightforward convergent protocol based on orthogonal chemoselective ligations to prepare structurally well-defined cyclopeptide-based homo- and heterovalent glycoconjugates displaying 5-N-acetyl-neuraminic acid (Neu5Ac), galactose (Gal), and/or N-acetyl glucosamine (GlcNAc). We first used copper-catalyzed azide-alkyne cycloaddition and/or thiol-ene coupling to conjugate propargylated α-sialic acid 3, β-GlcNAc thiol 5, and β-Gal thiol 6 onto cyclopeptide scaffolds 7-9 to prepare tetravalent homoglycoclusters (10-12) and hGCs (13-14) with 2:2 combinations of sugars...
October 2016: ChemistryOpen
https://www.readbyqxmd.com/read/27777840/mechanistic-investigation-into-olefin-epoxidation-with-h2o2-catalyzed-by-aqua-coordinated-sandwich-type-polyoxometalates-role-of-the-noble-metal-and-active-oxygen-position
#20
Chenggang Ci, Hongsheng Liu, Likai Yan, Zhongmin Su
Aqua-coordinated sandwich-type polyoxometalates (POMs), {[WZnTM2(H2O)2](ZnW9O34)2} (n-) (TM=Rh(III), Pd(II), and Pt(II)), catalyze olefin epoxidation with hydrogen peroxide and have been well established, and they present an advance toward the utilization of olefins. To elucidate the epoxidation mechanism, we systematically performed density functional calculations. The reaction proceeds through a two-step mechanism: activation of H2O2 and oxygen transfer. The aqua-coordinated complexes show two distinct H2O2 activation pathways: "two-step" and "concerted"...
October 2016: ChemistryOpen
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