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Cleve Dionel Mboyi, Carine Maaliki, Amelle Mankou Makaya, Yves Canac, Carine Duhayon, Remi Chauvin
With the view to enhancing the unique coordinating ability of the known phenyl-tetrakis(diisopropylamino)dicyclopropeniophosphine (Ph-DCP), replacement of the phenyl substituent by a tert-butyl substituent was envisaged. Both α-dicationic R-DCP phosphines, with R = Ph and (t)Bu, were prepared in 54%-55% yield by substitution of RPCl2 with two equivalents of bis(diisopropylamino)-dicyclopropenylidene (BAC) and metathesis with NaBF4. This method is implicitly consistent with the representation of R-DCPs as BAC-phosphenium adducts...
October 21, 2016: Inorganic Chemistry
Yulan Yu, Shengyi Zhuang, Ping Liu, Peipei Sun
Cyanomethylated coumarins were synthesized via cyanomethylation and cyclization of aryl alkynoates using cheap and available reagent acetonitrile as the cyanomethyl source in the presence of TBPB (tert-butyl peroxybenzoate) under transition metal-free conditions. For the substrates with various substituents on benzene ring, the reaction proceeded smoothly to give the corresponding products in moderate to good yields. The resulting products could be simply converted into some other related coumarin derivatives...
October 21, 2016: Journal of Organic Chemistry
Giulia Tuci, Lapo Luconi, Andrea Rossin, Enrico Berretti, Housseinou Ba, Massimo Innocenti, Dmitry Yakhvarov, Stefano Caporali, Cuong Pham-Huu, Giuliano Giambastiani
This paper describes the exohedral N-decoration of multi-walled carbon nanotubes (MWCNTs) with NH-aziridine groups via [2+1] cycloaddition of a tert-butyl-oxycarbonyl nitrene followed by controlled thermal decomposition of the cyclization product. The chemical grafting with N-containing groups deeply modifies the properties of the starting MWCNTs, generating new surface microenvironments with specific base (Brønsted) and electronic properties. Both these features translate into a highly versatile single-phase heterogeneous catalyst (MW@NAz) with remarkable chemical and electrochemical performance...
October 21, 2016: ACS Applied Materials & Interfaces
Liu-Zhu Yu, Yin Wei, Min Shi
Copper-catalyzed cascade cyclization of 1,5-enynes with two types of hypervalent reagents was developed via consecutive trifluoromethylazidation/diazidation and intramolecular click reaction (CUAAC), providing one-pot self-assembly of triazole fused isoindolines bearing a trifluoromethyl or an azide moiety. Moreover, the construction of a trifluoromethylcyclopropyl unit, which has been considered as a metabolically stable replacement for a tert-butyl moiety and was difficult to access, was also achieved under trifluoromethylazidation conditions...
October 21, 2016: Chemical Communications: Chem Comm
Atsushi Umehara, Hirofumi Ueda, Hidetoshi Tokuyama
A novel condensation reaction of carboxylic acids with various non-nucleophilic N-heterocycles and anilides was developed. The reaction proceeds in the presence of di-tert-butyl dicarbonate (Boc2O), catalytic 4-(dimethylamino)pyridine (DMAP), and 2,6-lutidine and is applicable to the acylation of a wide range of non-nucleophilic nitrogen compounds, including indoles, pyrroles, pyrazole, carbazole, lactams, oxazolidinones, and anilides with high functional group compatibility. The scope of indoles, carboxylic acids, and anilides was also studied...
October 21, 2016: Journal of Organic Chemistry
Hajime Suzuki, Takahiro Sakabe, Yuu Hirose, Toshihiko Eki
We aimed to develop the bioassays for genotixicity and/or oxidative damage using the recombinant yeast. A genotoxicity assay was developed using recombinant Saccharomyces cerevisiae strain BY4741 with a green fluorescent protein (GFP) reporter plasmid, driven by the DNA damage-responsive RNR3 promoter. Enhanced fluorescence induction was observed in DNA repair-deficient strains treated with methyl methanesulfonate, but not with hydrogen peroxide. A GFP reporter yeast strain driven by the oxidative stress-responsive TRX2 promoter was newly developed to assess oxidative damage, but fluorescence was poorly induced by oxidants...
October 21, 2016: Applied Microbiology and Biotechnology
Jing Li, Jun Zhou, Yuanhua Ye, Qunying Liu, Xiaojin Wang, Ning Zhang, Xietong Wang
BACKGROUND: Previous studies have shown that oxidative stress is an important factor in preeclampsia (PE). Heme oxygenase-1 (HO-1) and nuclear factor erythroid 2-related factor-2 (Nrf2) are protective proteins that are involved in combating oxidative stress in the body. Nrf2 is also an essential upstream transcription factor regulating HO-1. This study was aimed at exploring the physiological roles of HO-1 and Nrf2 in PE. METHODS: Serum and placenta were collected from 30 patients who presented with severe PE and 30 healthy pregnant females...
October 21, 2016: Gynecologic and Obstetric Investigation
Paula Boaventura, Rui Batista, Ana Pestana, Marta Reis, Adélia Mendes, Catarina Eloy, Manuel Sobrinho-Simoes, Paula Soares
Objective - The aim of this study is to evaluate the frequency and molecular characteristics of TERTp mutations in thyroid adenomas and carcinomas occurring in the low dose radiation exposure tinea capitis setting. Design and methods - Twenty seven patients with 34 well differentiated thyroid carcinomas and 28 patients with 29 follicular adenomas diagnosed in a Portuguese tinea capitis cohort of 1375 patients, were studied. Blood samples were obtained from all the patients. Screening for TERTp mutations was performed by PCR amplification followed by Sanger sequencing...
October 19, 2016: European Journal of Endocrinology
Supamas Danwittayakul, Supachai Songngam, Tipawan Fhulua, Panida Muangkasem, Sittha Sukkasi
Solar water disinfection (SODIS) is a simple point-of-use process that uses sunlight to disinfect water for drinking. Polyethylene terephthalate (PET) bottles are typically used as water containers for SODIS, but a new SODIS container design has recently been developed with low-density polyethylene (LDPE) bags and can overcome the drawbacks of PET bottles. Two nesting layers of LDPE bags are used in the new design: the inner layer containing the water to be disinfected and the outer one creating air insulation to minimize heat loss from the water to the surroundings...
October 19, 2016: Environmental Technology
Bice S Martincigh, Moses A Ollengo
The photostabilizing ability of grape seed extract on three common sunscreen absorbers: 2-ethylhexyl-p-methoxcinnamate (EHMC), benzophenone-3 (BP3) and tert-butylmethoxy dibenzoylmethane (BMDBM), was investigated. Samples were exposed to simulated solar radiation and monitored by spectrophotometric and chromatographic methods. The chemical composition of the grape seed extract was determined by GC-MS and HPLC-MS and the major secondary metabolites were found to be epicatechin and catechin. Exposure of the extract to UV radiation increased the UV absorption capacity of the extract...
October 19, 2016: Photochemistry and Photobiology
Aleksandar Antanasijevic, Nicholas J Hafeman, Smanla Tundup, Carolyn Kingsley, Rama K Mishra, Lijun Rong, Balaji Manicassamy, Duncan Wardrop, Michael Caffrey
The viral envelope protein hemagglutinin (HA) plays a critical role in influenza entry and thus is an attractive target for novel therapeutics. The small molecule tert-butylhydroquinone (TBHQ) has previously been shown to bind to HA and inhibit HA-mediated entry with low micromolar potency. However, enthusiasm for the use of TBHQ has diminished due to the compound's antioxidant properties. In this work we show that the antioxidant properties of TBHQ are not responsible for the inhibition of HA-mediated entry...
September 9, 2016: ACS Infectious Diseases
Shigeo Ohba, Joydeep Mukherjee, Tor-Christian Johannessen, Andrew Mancini, Tracy T Chow, Matthew Wood, Lindsey Jones, Tali Mazor, Roxanne E Marshall, Pavithra Viswanath, Kyle M Walsh, Arie Perry, Robert J A Bell, Joanna J Phillips, Joseph F Costello, Sabrina M Ronen, Russell O Pieper
Mutations in the isocitrate dehydrogenase gene IDH1 are common in lower-grade glioma where they result in the production of 2-hydroxyglutarate (2HG), disrupted patterns of histone methylation and gliomagenesis. IDH1 mutations also co-segregate with mutations in the ATRX gene and the TERT promoter, suggesting that IDH mutation may drive the creation or selection of telomere-stabilizing events as part of immortalization/transformation process. To determine if and how this may occur, we investigated the phenotype of pRb/p53-deficient human astrocytes engineered with IDH1 wild-type (WT) or R132H mutant (IDH1mut) genes as they progressed through their lifespan...
October 6, 2016: Cancer Research
Yu Zou, Huei Jinn Tong, Mingming Li, Kai Soo Tan, Tong Cao
The ability of human embryonic stem cells (hESCs) to proliferate indefinitely is attributed to its high telomerase activity and associated long telomere. However, factors regulating telomere length in hESCs remain largely uncharacterized. The aims of this study were, to identify factors which modulate telomere length of hESCs, and to determine if the telomere length of hESCs influences cellular senescence of its differentiated progeny cells. Telomerase reverse transcriptase (TERT) gene expression, telomerase activity and telomere length of hESCs cultured in different culture systems were compared...
October 18, 2016: Biogerontology
Ian Barnes, Peter Wiesen, Michael Gallus
Rate coefficients have been determined at (298 ± 2) K and atmospheric pressure for the reaction of OH radicals with two primary mono-alkyl, one secondary di-alkyl and five tertiary tri-alkyl substituted amines in a large volume photoreactor using the relative kinetic technique. The following rate coefficients (in cm3 molecule-1 s-1 units) have been obtained: 1,2-dimethylpropylamine, CH3C(CH3)HC(CH3)H)NH2: (5.08 ± 1.02) × 10-11; tert-amylamine (tert-pentylamine), CH3CH2C(CH3)2NH2: (0.86 ± 0.17) × 10-11; diethylamine, (CH3CH2)2NH: (7...
October 18, 2016: Journal of Physical Chemistry. A
Takuya Kanemitsu, Miho Sato, Miyuki Yoshida, Eisuke Ozasa, Michiko Miyazaki, Yuki Odanaka, Kazuhiro Nagata, Takashi Itoh
A highly enantioselective α-benzoyloxylation of malonic diester has been achieved by phase-transfer catalysis. The reaction of α-monosubstituted tert-butyl methyl malonate with benzoyl peroxide in the presence of aqueous KOH and N-(9-anthracenylmethyl)cinchoninium chloride afforded the corresponding α,α-disubstituted products in generally excellent chemical yields (up to 99% yield) with high enantioselectivities (up to 96% ee). In addition, the utility of this methodology was exhibited by the synthesis of a mineralocorticoid receptor antagonist...
October 18, 2016: Organic Letters
Karima Ait-Aissa, Joseph Hockenberry, David Gutterman, Aron Geurts, Andreas Beyer
OBJECTIVE: Flow mediated dilation (FMD) is the most physiological relevant form of endothelial-mediated vasodilation. Our laboratory has previously shown that telomerase, a ribo-nucleoprotein that counteracts telomere shortening, has a protective effect on endothelial function under conditions of oxidative stress in the human microcirculation. In the presence of coronary artery disease, decreased telomerase activity contributes to a shift in the mediator of FMD from atheroprotective nitric oxide (NO) to pro-inflammatory and atherogenic hydrogen peroxide (H2O2)...
September 2016: Journal of Hypertension
Manuela Balen, Gabriela Rotta Gomes, Jadel M Kratz, Cláudia M O Simões, Alexsandra Valério, Débora de Oliveira
Antioxidants are substances that defend cells against damage, kidnapping and destroying free radicals. They have been largely used in the food industry due the possibility to control the oxidation process, aimed to increase shelf life. Thus, esterification reaction to obtain ascorbyl linoleate catalyzed by Novozym 435 lipase assisted by ultrasound bath was investigated. In this work, molecular sieve (4 Å) was added to the reaction medium to remove the water formed during the esterification reaction to improve the process performance...
October 17, 2016: Bioprocess and Biosystems Engineering
Susoma Jannat, Md Yousof Ali, Hyeung-Rak Kim, Hyun Ah Jung, Jae Sue Choi
The aim of this study was to investigate the protective effects of juice powders from sweet orange [Citrus sinensis (L.) Osbeck], unshiu mikan (Citrus unshiu Marcow), and mini tomato (Solanum lycopersicum L.), and their major flavonoids, hesperidin, narirutin, and rutin in tert-butyl hydroperoxide (t-BHP)-induced oxidative stress in HepG2 cells. The increased reactive oxygen species and decreased glutathione levels observed in t-BHP-treated HepG2 cells were ameliorated by pretreatment with juice powders, indicating that the hepatoprotective effects of juice powders and their major flavonoids are mediated by induction of cellular defense against oxidative stress...
September 2016: Preventive Nutrition and Food Science
Ishfaq A Sheikh, Iftikhar A Tayubi, Ejaz Ahmad, Majid A Ganaie, Osama S Bajouh, Samera F AlBasri, Ibtihal M J Abdulkarim, Mohd A Beg
Environmental contamination has been one of the major drawbacks of the industrial revolution. Several man-made chemicals are constantly released into the environment during the manufacturing process and by leaching from the industrial products. As a result, human and animal populations are exposed to these synthetic chemicals on a regular basis. Many of these chemicals have adverse effects on the physiological functions, particularly on the hormone systems in human and animals and are called endocrine disrupting chemicals (EDCs)...
October 14, 2016: Ecotoxicology and Environmental Safety
Yuan Seng Wu, Ivy Chung, Won Fen Wong, Atsushi Masamune, Maw Shin Sim, Chung Yeng Looi
BACKGROUND: We previously showed that pancreatic stellate cells (PSC) secreted interleukin (IL)-6 and promoted pancreatic ductal adenocarcinoma (PDAC) cell proliferation via nuclear factor erythroid 2 (Nrf2)-mediated metabolic reprogramming. Epithelial-mesenchymal transition (EMT) is a key process for the metastatic cascade. To study the mechanism of PDAC progression to metastasis, we investigated the role of PSC-secreted IL-6 in activating EMT and the involvement of Nrf2 in this process...
October 14, 2016: Biochimica et Biophysica Acta
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