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https://www.readbyqxmd.com/read/28443507/synthesis-and-biological-activity-of-unnatural-enediynes
#1
Roberto Romeo, Salvatore V Giofrè, Maria A Chiacchio
The first reports of the natural enediyne anticancer antibiotics date back to the late 1980s; since then, a great deal of interest has been devoted to the chemistry, biology and potential medical applications of this family of compounds. The biological activity of enediynes is linked to the presence of a highly unsaturated hex-1-ene- 1,5-diyne system. The thermally induced transformation of this unit into a benzene  diradical (the Bergman cycloaromatization) is the key step of the antitumor properties of such compounds: 1,4-diaryl radicals are able to abstract H-atoms from the deoxyribose backbone of DNA, thus leading to DNA strand cleavage and ultimately cell death...
April 24, 2017: Current Medicinal Chemistry
https://www.readbyqxmd.com/read/28440645/structural-electronic-and-magnetic-properties-of-iron-disulfide-fens2-0-%C3%A2-n-1-6-clusters
#2
Slimane Tazibt, Aziz Chikhaoui, Said Bouarab, Andres Vega
The structural, electronic and magnetic properties of neutral and charged FenS2(0/±), n=1-6 clusters have been calculated in the framework of the density functional theory in the generalized gradient approximation for the exchange and correlation. The calculated adiabatic electron affinity and the vertical detachment energy are found to be in good agreement with the available experimental data. The impact of disulfide doping of the small iron clusters on the atomic structure, stability, magnetic moment and reactivity is determined through the analysis of the binding energy per atom, electronic charge transfer, spin-polarized electronic density of states and global reactivity indicators like the electronegativity and chemical hardness...
April 25, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28439586/direct-use-of-allylic-alcohols-and-allylic-amines-in-palladium-catalyzed-allylic-amination
#3
Jiangyan Jing, Xiaohong Huo, Jiefeng Shen, Jingke Fu, Qinghua Meng, Wanbin Zhang
Allylic alcohols and allylic amines were directly utilized in a Pd-catalyzed hydrogen-bond-activated allylic amination under mild reaction conditions in the absence of any additives. The cooperative action of a Pd-catalyst and a hydrogen-bonding solvent is most likely responsible for its high reactivity. The catalytic system is compatible with a variety of functional groups and can be used to prepare a wide range of linear allylic amines in good to excellent yields. Furthermore, this methodology can be easily applied to the one-step synthesis of two drugs, cinnarizine and naftifine, on a gram scale...
April 25, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28436454/gold-nanoparticle-polymer-nanocomposites-synthesized-by-room-temperature-atmospheric-pressure-plasma-and-their-potential-for-fuel-cell-electrocatalytic-application
#4
Ri-Chao Zhang, Dan Sun, Ruirui Zhang, Wen-Feng Lin, Manuel Macias-Montero, Jenish Patel, Sadegh Askari, Calum McDonald, Davide Mariotti, Paul Maguire
Conductive polymers have been increasingly used as fuel cell catalyst support due to their electrical conductivity, large surface areas and stability. The incorporation of metal nanoparticles into a polymer matrix can effectively increase the specific surface area of these materials and hence improve the catalytic efficiency. In this work, a nanoparticle loaded conductive polymer nanocomposite was obtained by a one-step synthesis approach based on room temperature direct current plasma-liquid interaction. Gold nanoparticles were directly synthesized from HAuCl4 precursor in poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)...
April 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28435964/kinetics-of-co2-diffusion-in-human-carbonic-anhydrase-a-study-using-molecular-dynamics-simulations-and-the-markov-state-model
#5
Gong Chen, Xian Kong, Diannan Lu, Jianzhong Wu, Zheng Liu
Molecular dynamics (MD) simulations, in combination with the Markov-state model (MSM), were applied to probe CO2 diffusion from an aqueous solution into the active site of human carbonic anhydrase II (hCA-II), an enzyme useful for enhanced CO2 capture and utilization. The diffusion process in the hydrophobic pocket of hCA-II was illustrated in terms of a two-dimensional free-energy landscape. We found that CO2 diffusion in hCA-II is a rate-limiting step in the CO2 diffusion-binding-reaction process. The equilibrium distribution of CO2 shows its preferential accumulation within a hydrophobic domain in the protein core region...
April 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28432884/use-of-presepsin-and-procalcitonin-for-prediction-of-septifast-results-in-critically-ill-patients
#6
Dunja Mihajlovic, Snezana Brkic, Arsen Uvelin, Biljana Draskovic, Vladimir Vrsajkov
PURPOSE: There is a need for identification of marker that could lead physicians to take the right step towards laboratory techniques for documentation of infection. The aim of this study was to investigate whether presepsin and procalcitonin (PCT) levels in patients with suspected sepsis could predict blood culture (BC) and SeptiFast (SF) results. MATERIAL AND METHODS: 100 patients were included in our study. PCT, C-reactive protein (CRP), and presepsin levels were determined...
April 8, 2017: Journal of Critical Care
https://www.readbyqxmd.com/read/28431335/minimization-of-the-amount-of-kryptofix-222-khco3-for-applications-to-microscale-18-f-radiolabeling
#7
Ren Iwata, Claudio Pascali, Kazunori Terasaki, Yoichi Ishikawa, Shozo Furumoto, Kazuhiko Yanai
Conversion of aqueous [(18)F]fluoride to reactive [(18)F]fluoride is an important first step in the radiosynthesis of (18)F-labeled compounds by nucleophilic substitution. A versatile method for the rapid preparation of reactive [(18)F]fluoride by the combined use of an Oasis MAX cartridge and a methanolic solution of the Kryptofix 222-KHCO3 complex (K.222/KHCO3) was developed. The latter amount was optimized with the aim to keep it as low as possible while achieving recovery yields of [(18)F]fluoride comparable to those attained with the commonly used QMA cartridge...
April 13, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28430609/characterization-of-pressure-mediated-vascular-tone-in-resistance-arteries-from-bile-duct-ligated-rats
#8
Ravirajsinh N Jadeja, Menaka C Thounaojam, Sandeep Khurana
In cirrhosis, changes in pressure-mediated vascular tone, a key determinant of systemic vascular resistance (SVR), are unknown. To address this gap in knowledge, we assessed ex vivo dynamics of pressurized mesenteric resistance arteries (diameter ~ 260 μm) from bile duct-ligated (BDL) and sham-operated (SHAM) rats and determined the underlying mechanisms. At isobaric intraluminal pressure (70 mmHg) as well as with step-wise increase in pressure (10-110 mmHg), arteries from SHAM-rats constricted more than BDL-rats, and had reduced luminal area...
February 16, 2017: Oncotarget
https://www.readbyqxmd.com/read/28430279/microcontact-printing-with-aminosilanes-creating-biomolecule-micro-and-nanoarrays-for-multiplexed-microfluidic-bioassays
#9
Shivani Sathish, Sébastien G Ricoult, Kazumi Toda-Peters, Amy Q Shen
Microfluidic systems integrated with protein and DNA micro- and nanoarrays have been the most sought-after technologies to satisfy the growing demand for high-throughput disease diagnostics. As the sensitivity of these systems relies on the bio-functionalities of the patterned recognition biomolecules, the primary concern has been to develop simple technologies that enable biomolecule immobilization within microfluidic devices whilst preserving bio-functionalities. To address this concern, we introduce a two-step patterning approach to create micro- and nanoarrays of biomolecules within microfluidic devices...
April 21, 2017: Analyst
https://www.readbyqxmd.com/read/28429736/single-step-one-pot-synthesis-of-tio2-nanosheets-doped-with-sulfur-on-reduced-graphene-oxide-with-enhanced-photocatalytic-activity
#10
Weilin Wang, Zhaofeng Wang, Jingjing Liu, Zhu Luo, Steven L Suib, Peng He, Guqiao Ding, Zhengguo Zhang, Luyi Sun
A hybrid photocatalyst based on anatase TiO2 was designed by doping TiO2 with sulfur and incorporating reduced graphene oxide (TiO2-S/rGO hybrid), with an aim to narrow the band gap to potentially make use of visible light and decrease the recombination of excitons, respectively. This TiO2-S/rGO hybrid was successfully synthesized using a one-pot hydrothermal method via single-step reaction. The structure and morphology of the TiO2-S/rGO hybrid catalyst was carefully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS)...
April 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28428179/adamts13-controls-vascular-remodeling-by-modifying-vwf-reactivity-during-stroke-recovery
#11
Haochen Xu, Yongliang Cao, Xing Yang, Ping Cai, Lijing Kang, Ximin Zhu, Haiyu Luo, Lu Lu, Lixiang Wei, Xiaofei Bai, Yuanbo Zhu, Bing-Qiao Zhao, Wenying Fan
Angiogenic response is essential for ischemic brain repair. However, the mechanisms leading to postischemic neovascularization have not been established, and no therapies have been identified. The VWF-cleaving protease ADAMTS13 is required for endothelial tube formation in vitro However, there is currently no in vivo evidence supporting a function of ADAMTS13 in angiogenesis. Here we show that mice deficient in ADAMTS13 exhibited significantly reduced neovascularization, brain capillary perfusion, pericyte and smooth muscle cell coverage on microvessels, expression of the tight junction and basement membrane proteins, and accelerated blood-brain barrier (BBB) breakdown and extravascular deposits of serum proteins in the peri-infarct cortex at 14 days after stroke...
April 20, 2017: Blood
https://www.readbyqxmd.com/read/28427676/ultrasonic-assisted-reactive-extraction-is-a-fast-and-easy-method-for-biodiesel-production-from-jatropha-curcas-oilseeds
#12
Gajendra Kumar
The alkyl ester of vegetable oil represents as an alternative fuel for diesel engines which is to reduce the cost of biodiesel by increasing the efficiency of biodiesel production by single step reaction i.e. production of biodiesel by combing extraction of oil from oilseed and reaction of extract with alcohol by using ultrasonication. This process is called ultrasonic reactive-extraction. It consists of the investigation of the optimum conditions i.e. seed size >1-<2, molar ratio oilseed to methanol 1:100, catalyst concentration 1...
July 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28427269/spatially-selective-binding-of-green-fluorescent-protein-on-designed-organosilane-nanopatterns-prepared-with-particle-lithography
#13
Zachary L Highland, Jayne C Garno
A practical approach for preparing protein nanopatterns has been to design surface templates of nanopatterns of alkanethiols or organosilanes that will selectively bind and localize the placement of biomolecules. Particle lithography provides a way to prepare millions of protein nanopatterns with a few basic steps. For our nanopatterning strategy, organosilanes with methoxy and sulfhydryl groups were chosen as a surface template. Green fluorescent protein (GFP) was selected as a model for patterning. Areas of 2-[methoxy (polyethyleneoxy)6-9propyl]trichlorosilane (MPT-silane) are effective as a matrix for resisting the attachment of proteins, whereas nanopatterns with sulfur groups provide reactive sites for binding linker groups to connect proteins...
April 19, 2017: Biointerphases
https://www.readbyqxmd.com/read/28426080/c-reactive-protein-and-interleukin-6-microfluidic-immunoassays-with-on-chip-pre-stored-reagents-and-centrifugo-pneumatic-liquid-control
#14
Y Zhao, G Czilwik, V Klein, K Mitsakakis, R Zengerle, N Paust
We present a fully automated centrifugal microfluidic method for particle based protein immunoassays. Stick-pack technology is employed for pre-storage and release of liquid reagents. Quantitative layout of centrifugo-pneumatic particle handling, including timed valving, switching and pumping is assisted by network simulations. The automation is exclusively controlled by the spinning frequency and does not require any additional means. New centrifugal microfluidic process chains are developed in order to sequentially supply wash buffer based on frequency dependent stick-pack opening and pneumatic pumping to perform two washing steps from one stored wash buffer; pre-store and re-suspend functionalized microparticles on a disk; and switch between the path of the waste fluid and the path of the substrate reaction product with 100% efficiency...
April 20, 2017: Lab on a Chip
https://www.readbyqxmd.com/read/28426079/oxidation-suppression-during-hydrothermal-phase-reversion-allows-synthesis-of-monolayer-semiconducting-mos2-in-stable-aqueous-suspension
#15
Zhongying Wang, Yin-Jia Zhang, Muchun Liu, Andrew Peterson, Robert H Hurt
This letter demonstrates a simple method to achieve high-yields of 1H semiconducting MoS2 monolayers in concentrated, colloidally-stable aqueous suspension. The method is based on oxidation suppression during the hydrothermal processing step used for metal-to-semiconductor phase reversion. Accompanying DFT calculations on elementary steps in the MoS2 wet oxidation reaction suggest that a two-site corrosion mechanism is responsible for the observed high reactivity and low stability of 1T metallic MoS2.
April 20, 2017: Nanoscale
https://www.readbyqxmd.com/read/28425184/enantioselective-synthesis-of-mitomycin%C3%A2-k-by-a-palladium-catalyzed-oxidative-tandem-cyclization
#16
Qiang-Shuai Gu, Dan Yang
The mitomycins, a family of bioactive natural products, feature a compact 6/5/5-fused polycyclic ring structure densely decorated with highly reactive and/or fragile quinone, amino ketal, and aziridine as well as carbamate moieties. It is this striking feature that has defeated numerous synthetic attempts towards these apparently small molecules, rendering them one of the most formidable targets for total synthesis. We herein report the first enantioselective synthesis of (+)-mitomycin K, a representative of G series mitomycins...
April 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28423654/mcl-1-regulates-reactive-oxygen-species-via-nox4-during-chemotherapy-induced-senescence
#17
Abeba Demelash, Lukas W Pfannenstiel, Li Liu, Brian R Gastman
Mcl-1, a Bcl-2 family member, is highly expressed in a variety of human cancers and is believed to enhance tumorigenic potential and chemotherapy resistance through the inhibition of apoptosis and senescence. We previously reported that Mcl-1's regulation of chemotherapy-induced senescence (CIS) is dependent on its ability to prevent reactive oxygen species (ROS) generation. In this report, we demonstrate that Mcl-1-regulated CIS requires not only ROS, but specifically mitochondrial ROS, and that these events are upstream of activation of the DNA damage response, another necessary step toward senescence...
March 7, 2017: Oncotarget
https://www.readbyqxmd.com/read/28422498/selective-oxygenation-of-cyclohexene-by-dioxygen-via-an-iron-v-oxo-complex-autocatalyzed-reaction
#18
Muniyandi Sankaralingam, Yong-Min Lee, Wonwoo Nam, Shunichi Fukuzumi
An iron complex with a tetraamido macrocyclic ligand, [(TAML)Fe(III)](-), was found to be an efficient and selective catalyst for allylic oxidation of cyclohexene by dioxygen (O2); cyclohex-2-enone was obtained as the major product along with cyclohexene oxide as the minor product. An iron(V)-oxo complex, [(TAML)Fe(V)(O)](-), which was formed by activating O2 in the presence of cyclohexene, initiated the autoxidation of cyclohexene with O2 to produce cyclohexenyl hydroperoxide, which reacted with [(TAML)Fe(III)](-) to produce [(TAML)Fe(V)(O)](-) by autocatalysis...
April 19, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28422329/metal-complexes-of-a-redox-active-1-phosphaferrocenophane-structures-electrochemistry-and-redox-switchable-catalysis
#19
Alexander Feyrer, Markus Armbruster, Karin Fink, Frank Breher
The synthesis and characterisation of several metal complexes of a redox-switchable, mesityl(Mes)-substituted [1]phosphaferrocenophane, FcPMes (1), are reported. Cyclic voltammetry studies on the bimetallic complexes [M(κ1P-1)(cod)Cl] (M = Rh: 2; M = Ir: 4), [Rh(κ1P-1)2(CO)Cl] (3) and [AuCl(κ1P-1)] (5), in conjunction with DFT calculations, provided indications for a good electronic communication between the metal atoms. In order to confirm that the ferrocenophane unit might be able to electrochemically influence the reactivity of the coordinated transition metal, the rhodium complex 2 was employed as redox-switchable catalyst in the hydrosilylation of terminal alkynes...
April 19, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28422167/biotin-transfer-from-a-trifunctional-crosslinker-for-identification-of-cell-surface-receptors-of-soluble-protein-ligands
#20
Tammy-Lynn Tremblay, Jennifer J Hill
Here we describe a novel crosslinker and its application as a biotin-transfer reagent to identify cell surface receptors of soluble protein ligands on live cells. This crosslinker contains three functional groups: an aldehyde-reactive aminooxy group, a sulfhydryl, and a biotin (ASB). It is readily synthesized via a 3-step addition reaction using standard solid-phase peptide synthesis methods and commercially available intermediates, allowing access to laboratories without specialized synthetic chemistry capabilities...
April 19, 2017: Scientific Reports
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