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Benjamin J Stenton, Bruno L Oliveira, Maria J Matos, Laura Sinatra, Gonçalo J L Bernardes
We describe the development of a bifunctional linker that simultaneously allows site-specific protein modification and palladium-mediated bioorthogonal decaging. This was enabled by a thioether binding motif in the propargyl carbamate linker and a readily available palladium complex. We demonstrate the efficiency of this reaction by controlled drug release from a PEGylated doxorubicin prodrug in cancer cells. The linker can be easily installed into cysteine bearing proteins which we demonstrated for the construction of an anti-HER2 nanobody-drug conjugate...
May 7, 2018: Chemical Science
Yingchao Li, Yongjun Wang, Ran Zhang, Cuiru Liu, Yue Wei, Jin Sun, Zhonggui He, Youjun Xu, Tianhong Zhang
Tapentadol suffers from rapid clearance due to extensive metabolism in vivo, which results in low oral bioavailability. In the present study, three novel prodrugs of tapentadol (WWJ01, WWJ02, and WWJ03) were synthesized to improve its metabolic stability and thereby improve its oral bioavailability. They all exhibited good stability in phosphate buffers, simulated gastrointestinal fluids, rat plasma, and intestinal and liver homogenates. Disappointingly, the N,N-diethylcarbamate prodrug of tapentadol (WWJ02) and the N,N-diisopropylcarbamate prodrug of tapentadol (WWJ03) were metabolized into inactive metabolites when incubated with liver microsomes...
May 17, 2018: Drug Delivery and Translational Research
Mauro Safir Filho, Pascal Dao, Maéva Gesson, Anthony R Martin, Rachid Benhida
We report the development of four novel fluorescent probes to monitor the activity of the β-galactosidase enzyme (β-gal), in vitro and in living cells. The fluorophores are based on a 6-amino-styryl-benzothiazole push-pull core and display a strong ICT emission. The probes encompass the fluorescent motif that is connected to a β-d-galactopyranoside moiety through a self-immolative benzyl carbamate linker (βGal-1-4). The screening of four different fluorophores enabled us to access new light-up and two-band ratiometric reporters...
May 18, 2018: Analyst
Cheng Zhu, Robert Frigge, Andrew M Turner, Ralf I Kaiser, Bing-Jian Sun, Si-Ying Chen, Agnes H H Chang
The hitherto elusive phosphino formic acid molecule (H2PCOOH) was detected for the first time in the gas phase. Theoretical calculations revealed an unexpected kinetic stability of H2PCOOH compared to the isovalent carbamic acid (H2NCOOH) although the replacement of a single nitrogen atom by phosphorus decreases the bond order from a partial double (-C[double bond, length as m-dash]N-) to a single (-C-P-) bond. This work provides a fundamental framework to explore the synthesis and stability of derivatives of carbonic acid (H2CO3), in which one or both hydroxyl groups (OH) are replaced by hydride moieties involving third row atoms...
May 18, 2018: Chemical Communications: Chem Comm
Constantina Rousidou, Dionysis Karaiskos, Despoina Myti, Evangelos Karanasios, Panagiotis A Karas, Maria Tourna, Emmanuel A Tzortzakakis, Dimitrios G Karpouzas
No abstract text is available yet for this article.
June 1, 2018: FEMS Microbiology Ecology
Yasunori Okamoto, Ryosuke Kojima, Fabian Schwizer, Eline Bartolami, Tillmann Heinisch, Stefan Matile, Martin Fussenegger, Thomas R Ward
Complementing enzymes in their native environment with either homogeneous or heterogeneous catalysts is challenging due to the sea of functionalities present within a cell. To supplement these efforts, artificial metalloenzymes are drawing attention as they combine attractive features of both homogeneous catalysts and enzymes. Herein we show that such hybrid catalysts consisting of a metal cofactor, a cell-penetrating module, and a protein scaffold are taken up into HEK-293T cells where they catalyze the uncaging of a hormone...
May 16, 2018: Nature Communications
Huicong Zhang, Kuanglei Wang, Kexin Na, Dan Li, Zhenbao Li, Dongyang Zhao, Lu Zhong, Menglin Wang, Longfa Kou, Cong Luo, Haotian Zhang, Qiming Kan, Huaiwei Ding, Zhonggui He, Jin Sun
To address the challenge of rapid enzyme inactivation, poor tumor targeting, acquired drug resistance in gemcitabine (GEM) application, we report two groups of maleimide-functionalised GEM prodrugs conjugating covalently in situ with cys-34 of blood-circulating albumin, resulting in macromolecular prodrugs after intravenous administration. Specially, tailored and accurate controlled release was achieved through different combinations of linkage bonds relatively stable and labile (carbamate and carbonate, respectively) and linkers with or without insertion of a disulfide bond...
May 16, 2018: Journal of Medicinal Chemistry
Hayoung Song, Hyunho Kim, Eunsung Lee
Herein, a coumaraz-2-on-4-ylidene (1) as a new example of ambiphilic N-heterocyclic carbenes with fine tunable electronic properties is reported. The N-carbamic and aryl groups on carbene carbon provide exceptionally high electrophilicity and nucleophilicity simultaneously to the carbene center, as evidenced by the 77Se NMR chemical shifts of their selenoketone derivatives and the CO stretching strengths of their rhodium carbonyl complexes. Since the precursors of 1 could be synthesized from various functionalized Schiff bases in a practical and scalable manner, the electronic properties of 1 can be fine-tuned in quantitative and predictable way using the Hammett σ constant of the functional groups on aryl ring...
May 16, 2018: Angewandte Chemie
Rapidah Mohamad, Normah Awang, Nurul Farahana Kamaludin, Mukesh M Jotani, Edward R T Tiekink
The crystal and mol-ecular structures of the two title organotin di-thio-carbamate compounds, [Sn(C4 H9 )2 (C7 H14 NO2 S2 )2 ], (I), and [Sn(C6 H5 )3 (C5 H10 NOS2 )], (II), are described. Both structures feature asymmetrically bound di-thio-carbamate ligands leading to a skew-trapezoidal bipyramidal geometry for the metal atom in (I) and a distorted tetra-hedral geometry in (II). The complete mol-ecule of (I) is generated by a crystallographic twofold axis (Sn site symmetry 2). In the crystal of (I), mol-ecules self-assemble into a supra-molecular array parallel to (10-1) via methyl-ene-C-H⋯O(meth-oxy) inter-actions...
March 1, 2018: Acta Crystallographica. Section E, Crystallographic Communications
Ruben Canton-Vitoria, Lorenzo Vallan, Esteban Urriolabeitia, Ana Benito, Wolfgang Maser, Nikos Tagmatarchis
We report on the preparation, characterization and photophysical and electrocatalytic properties of carbon dots (CDs)/MoS2 ensembles. Based on electrostatic interactions, ammonium functionalized MoS2, prepared upon reaction of 1,2-dithiolane tert-butyl carbamate with MoS2 followed by acidic deprotection, was coupled with CDs bearing multiple carboxylates on their periphery as derived upon microwave-assisted polycondensation of citric acid and ethylenediamine followed by alkaline treatment. Insights into electronic interactions between the two species within CDs/MoS2 emanated from absorption and photoluminescence titration assays...
May 15, 2018: Chemistry: a European Journal
Ulrich Woiwode, Martina Ferri, Norbert M Maier, Wolfgang Lindner, Michael Lämmerhofer
A cardinal requirement for effective 2D-HPLC separations is sufficient complementarity in the retention profiles of first and second dimension separations. It is shown that retention and enantioselectivity of chiral selectors derived from cinchona alkaloids can be conveniently modulated by structural variation of the carbamate residue of the quinine/quinidine carbamate ligand of such chiral stationary phases (CSP). A variety of aliphatic and aromatic residues have been tested in comparison to non-carbamoylated quinine CSP...
April 27, 2018: Journal of Chromatography. A
Cherng Shii Leong, Indra Vythilingam, Meng Li Wong, Wan-Yusoff Wan Sulaiman, Yee Ling Lau
The resistance status of Selangor Aedes aegypti (Linnaeus) larvae against four major groups of insecticides (i.e., organochlorines, carbamates, organophosphates and pyrethroids) was investigated. Aedes aegypti were susceptible against temephos (organophosphate), although resistance (RR50  = 0.21 - 2.64) may be developing. The insecticides susceptibility status of Ae. aegypti larvae were found heterogeneous among the different study sites. Results showed that Ae. aegypti larvae from Klang, Sabak Bernam and Sepang were susceptible against all insecticides tested...
May 11, 2018: Acta Tropica
Zainab M Khoder, Christina E Wong, Sherry R Chemler
A convenient copper-catalyzed intramolecular/intermolecular alkene diamination reaction to synthesize 3-aminomethyl-functionalized isoxazolidines under mild reaction conditions and with generally high levels of diastereoselectivity was achieved. This reaction demonstrates that previously underutilized unsaturated carbamates are good [Cu]-catalyzed diamination substrates. Sulfonamides, anilines, benzamide, morpholine, and piperidine can serve as the external amine source. This relatively broad amine range is attributed to the mild reaction conditions...
July 7, 2017: ACS Catalysis
Xiaoxin Chen, Sheng He, Zhibin Liang, Qing X Li, Hai Yan, Jiye Hu, Xiaolu Liu
Pyraclostrobin has been widely and long-termly applicated to agricultural fields. The removal of pyraclostrobin from ecological environment has received wide attention. In this study, using sequential enrichments with pyraclostrobin as a sole carbon source, two microbial communities (HI2 and HI6) capable of catabolizing pyraclostrobin were obtained from Hawaiian soils. The microfloras analysis indicated that only Proteobacteria and Bacteroides could survive in HI2-soil after acclimatization, whereas the number of Proteobacteria in HI6-soil accounted for more than 99%...
April 27, 2018: Journal of Hazardous Materials
A F Ahmeda, M G Rae, L M Anweigi, M F Al Otaibi, A A Al-Masri, E J Johns
A significant factor in the development of hypertension may be excessive vasoconstriction within the renal medulla. This study therefore investigated the role of superoxide dismutase (SOD) in the regulation of renal medullary and cortical blood perfusion (MBP and CBP respectively) in both stroke-prone spontaneously hypertensive rats (SHRSP) and normotensive Wistar rats. CBP and MBP were measured before and after intra-renal infusion of the SOD inhibitor, diethyldithio-carbamic acid (DETC). Under basal conditions, mean arterial pressure was significantly greater in SHRSP than Wistar rats, but both MBP and heart rate (HR) were significantly lower in SHRSP relative to Wistar rats (P < 0...
May 10, 2018: Physiological Research
Fiacre R Agossa, Gil G Padonou, Come Z Koukpo, Jacques Zola-Sahossi, Roseric Azondekon, Osei K Akuoko, Juniace Ahoga, Boris N'dombidje, Bruno Akinro, Arsene Jacques Y H Fassinou, Michel Sezonlin, Martin C Akogbeto
BACKGROUND: Scale-up of the distribution of long-lasting insecticide-treated bed nets and indoor residual spraying with insecticides over the last decade have contributed to the considerable decrease of malaria morbidity and mortality in sub-Saharan Africa. Due to the increasing pyrethroid resistance intensity and the spread of carbamate resistance in Anopheles gambiae (s.s.) mosquitoes and the limited number of insecticides recommended by the WHO for vector control, alternative insecticide formulations for IRS with long-lasting residual activity are required to sustain the gains obtained in most malaria-endemic countries...
May 10, 2018: Parasites & Vectors
Ron M Versteegen, Wolter Ten, Raffaella Rossin, Mark Ar de Geus, Henk M Janssen, Marc Stefan Robillard
The bioorthogonal cleavage of allylic carbamates from trans-cyclooctene (TCO) upon reaction with tetrazine is widely used to release amines. We disclose here that this reaction can also cleave TCO esters, carbonates, and, surprisingly, ethers. Mechanistic studies demonstrated that the elimination is mainly governed by the formation of the rapidly eliminating 1,4-dihydropyridazine tautomer, and less by the nature of the leaving group. In contrast to the widely used p-aminobenzyloxy linker, which affords a slow cleavage of aromatic but not of aliphatic ethers, the aromatic, benzylic and aliphatic TCO ethers cleaved as efficiently as the carbamate, carbonate and esters...
May 10, 2018: Angewandte Chemie
Aleksandra Narczyk, Michał Pieczykolan, Sebastian Stecko
A synthesis of non-racemic β-alkyl-β-aryl allyl alcohols and their transformation into allylamines bearing a quaternary stereogenic center is reported. The allyl alcohols were prepared either by Cu-catalyzed enantioselective reduction of enones or by sequential alkylation/hydrostannylation/Stille coupling of non-racemic propargyl alcohols. The prepared β-alkyl-β-aryl allyl alcohols were converted (after carbamoylation) to the corresponding allylamine derivatives through cyanate-to-isocyanate rearrangement/nucleophilic addition with complete chirality transfer...
May 10, 2018: Organic & Biomolecular Chemistry
David Vela-Corcía, Diego Romero, Antonio de Vicente, Alejandro Pérez-García
Methyl benzimidazole carbamate (MBC) fungicides are fungicidal compounds that exert their biological activities by preventing cell division through the inhibition of tubulin polymerization, which is the major component of microtubules. Several mutations in the β-tubulin gene contribute to MBC resistance, the most common and significant of which occur at residues 198 and 200. Despite nearly 50 years of agricultural use, the binding site of MBCs and the precise mechanism by which those mutations affect fungicide efficacy have not been determined...
May 8, 2018: Scientific Reports
Vasanthan Ravichandran, Venkitasamy Kesavan, Sandrine Cojean, Philippe M Loiseau, Athipettah Jayakrishnan
BACKGROUND: Amphotericin B (AmB), a polyene antibiotic used for the treatment of fungal and leishmanial infections is virtually insoluble in water and exhibits severe toxicity. AmB has been conjugated to various soluble polymers for improving its solubility and reducing its toxicity. Conjugating AmB to a polysorbate surfactant such as polyoxyethylene sorbitan monolaurate (Tween 20), was examined to improve its solubility and reduce its toxicity. METHODS: AmB was coupled to Tween 20 via carbamate linkage at 15 and 30 wt% concentrations in high yield by activating the hydroxyl groups of the surfactant using p- nitrophenyl chloroformate...
May 3, 2018: Current Drug Delivery
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