195,209 results match your criteria bond


Distinct phosphorylation profiles of tau in brains of patients with different tauopathies.

Neurobiol Aging 2021 Aug 21;108:72-79. Epub 2021 Aug 21.

Department of Biological Sciences, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Tokyo, Japan; Department of Dementia and Higher Brain Function, Tokyo Metropolitan Institute of Medical Science, Setagaya, Tokyo, Japan. Electronic address:

Tauopathies are neurodegenerative diseases that are characterized by pathological accumulation of tau protein. Tau is hyperphosphorylated in the brain of tauopathy patients, and this phosphorylation is proposed to play a role in disease development. However, it has been unclear whether phosphorylation is different among different tauopathies. Read More

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A novel methylenemalononitrile-BODIPY-based fluorescent probe for highly selective detection of hydrogen peroxide in living cells.

Eur J Med Chem 2021 Sep 6;226:113828. Epub 2021 Sep 6.

School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Shenzhen, 518107, PR China. Electronic address:

Hydrogen peroxide (HO) plays vital roles in oxidative stress and signal transduction in living organisms, and its abnormal levels could be linked to many diseases. Despite numerous efforts spent, it is still urgent and of high importance to develop better HO probes with good selectivity, high sensitivity and low backgrounds. To this end, a novel boron dipyrromethene (BODIPY)-based fluorescent probe with an electron-withdrawing methylenemalononitrile at the meso position has been rationally designed, successfully synthesized and investigated for detection of HO in aqueous solutions and living cells, which exhibited high selectivity and sensitivity, fluorescent "turn-on" phenomenon at 540 nm, and ratiometric changes from 506 to 540 nm. Read More

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September 2021

A comprehensive overview of social network measures for older adults: A systematic review.

Arch Gerontol Geriatr 2021 Sep 11;97:104525. Epub 2021 Sep 11.

Centre for Health Systems and Safety Research, Australian Institute of Health Innovation, Macquarie University, NSW, Australia. Electronic address:

Objectives: The size and type of older adults' social networks is associated with health, mental and social outcomes. Investigators within many disciplines are now measuring social networks, but it is not always clear what they are assessing, or which measures may best meet their objectives. To undertake a systematic review to identify (i) social network measures used for older adults, (ii) variety of social network dimensions and (iii) how measures have developed over time. Read More

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September 2021

Site-Fixed Hydroboration of Terminal and Internal Alkenes using BX3/iPr2NEt.

Angew Chem Int Ed Engl 2021 Sep 18. Epub 2021 Sep 18.

Lanzhou Institute of Chemical Physics, CAS, State Key Laboratory for Oxo Synthesis and Selective Oxidation, Tianshui Middle Road, 730000, Lanzhou, CHINA.

An unprecedented and general hydroboration of alkenes with BX3(X = Br, Cl) as the boration reagent in the presence of iPr2NEt is reported. The addition of iPr2NEt not only suppresses alkene polymerization and haloboration side reactions but also provides an "H" source for hydroboration. More importantly, the site-fixed installation of a boryl group at the original position of the internal double-bond is readily achieved as compared with conventional transition-metal-catalyzed hydroboration processes. Read More

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September 2021

Direct, Site-Selective and Redox-Neutral α-C-H Bond Functionalization of Tetrahydrofurans via Quantum Dots Photocatalysis.

Angew Chem Int Ed Engl 2021 Sep 18. Epub 2021 Sep 18.

Technical Institute of Physics and Chemistry, Technical Institute of Physics and Chemistry, CAS, CHINA.

As one of the most ubiquitous bulk reagents available, the intrinsic chemical inertness of tetrahydrofuran (THF) makes direct and site-selective C(sp 3 )-H bond activation difficult, especially under redox neutral condition. Here, we demonstrate that semiconductor quantum dots (QDs) can activate α-C-H bond of THF via forming QDs/THF conjugates. Under visible light irradiation, the resultant alkoxyalkyl radical directly engages in radical cross-coupling with α-amino radical from amino C-H bonds or radical addition with alkene or phenylacetylene, respectively. Read More

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September 2021

Theoretical study on pentiptycene molecular brake: photoinduced isomerization and photoinduced electron transfer.

J Mol Model 2021 Sep 18;27(10):289. Epub 2021 Sep 18.

Key Laboratory for Green Organic Synthesis and Application of Hunan Province, Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan, Hunan, 411105, People's Republic of China.

The isomerization of the double bond plays an important role in the braking and de-braking of the light-controlled molecular brake. Therefore, the pentiptycene-type (Pp-type) light-controlled molecular brake system ((E)- and (Z)-4'-pentiptycyl vinyl-[1,1'-biphenyl]-4-carbonitrile) containing the C = C double bond was theoretically studied. Combining the 6-31G(d) basis set, the ωB97XD functional with dispersion correction was applied to implement the (E)-configuration and (Z)-configuration initial optimization. Read More

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September 2021

Hybridization of tumor homing and mitochondria-targeting peptide domains to design novel dual-imaging self-assembled peptide nanoparticles for theranostic applications.

Drug Deliv Transl Res 2021 Sep 17. Epub 2021 Sep 17.

College of Chemistry and Chemical Engineering, Gansu Province, Lanzhou University, Lanzhou-730000, People's Republic of China.

A novel hybridized dual-targeting peptide-based nanoprobe was successfully designed by using the cyclic heptapeptide. This peptide has Arg-Gly-Asp-Lys-Leu-Ala-Lys sequence, in which the RGD homing motif and KALK mitochondria-targeting motif were linked via amide bond. The designed peptide probe was further modified through covalent linkage to induce dual-imaging functionality, and self-assembled to form spherical nanoparticles. Read More

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September 2021

Development of a new biocathode for a single enzyme biofuel cell fuelled by glucose.

Sci Rep 2021 Sep 17;11(1):18568. Epub 2021 Sep 17.

Nanotechnas - Center of Nanotechnology and Materials Science, Institute of Chemistry, Faculty of Chemistry and Geosciences, Vilnius University, Naugarduko st. 24, 03225, Vilnius, Lithuania.

In this study, we reported the development of Prussian blue (PB), poly(pyrrole-2-carboxylic acid) (PPCA), and glucose oxidase (GOx) biocomposite modified graphite rod (GR) electrode as a potential biocathode for single enzyme biofuel cell fuelled by glucose. In order to design the biocathode, the GR electrode was coated with a composite of PB particles embedded in the PPCA shell and an additional layer of PPCA by cyclic voltammetry. Meanwhile, GOx molecules were covalently attached to the carboxyl groups of PPCA by an amide bond. Read More

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September 2021

Spontaneous breathing during high-frequency oscillation revealed by diaphragm electrical activity.

Pediatr Neonatol 2021 Sep 3. Epub 2021 Sep 3.

Keenan Research Centre for Biomedical Science and Department of Critical Care Medicine, St. Michael's Hospital, 30 Bond Street, Toronto, ON, M5B1W8, Canada; Department of Medicine, University of Toronto, Toronto, Canada.

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September 2021

Clinical debriefing in the emergency department.

Emerg Med Australas 2021 Oct;33(5):778-779

Emergency Department, Gold Coast Hospital and Health Service, Gold Coast, Queensland, Australia.

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October 2021

Dimerization in α-TiCl3 and α-TiBr3: The DFT study.

J Phys Condens Matter 2021 Sep 17. Epub 2021 Sep 17.

Ural Branch RAS, Russian Academy of Sciences - Institute of Metal Physics, Kovalevskaya st., 18,, Ekaterinburg, RUSSIA, Ekaterinburg, 620137, RUSSIAN FEDERATION.

A series of DFT calculations for two layered compounds with honeycomb lattice - α-TiCl3 and α-TiBr3 has been performed. It was shown that the symmetric SU(4) spin-orbital model recently proposed for d1 systems with honeycomb lattice can not be realized in these titanates because they dimerize in the low temperature phase. This explains experimentally observed drop in magnetic susceptibility of α-TiBr3. Read More

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September 2021

A DFT study of the double (3 + 2) cycloaddition of nitrile oxides and allenoates for the formation of spirobiisoxazolines.

J Mol Graph Model 2021 Sep 12;109:108033. Epub 2021 Sep 12.

Theoretical and Computational Chemistry Laboratory, Department of Chemistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. Electronic address:

The molecular mechanism of the double (3 + 2) cycloaddition (32CA) reaction between nitrile oxides and allenoates has been studied using density functional theory at the M06-2X/6-311G (d,p) level of theory. In the first 32CA, the nitrile oxide adds chemo- and regio-selectively to the C-C double bond of the allenoate closest to the carboxylate group followed by a subsequent regioselective addition to the olefinic bond of the isoxazoline intermediate. The rate constant for the preferred pathway (formation of 4-methylene-2-isoxazoline intermediate) in the reaction of ethyl substituted allenoate and mesitonitrile oxide is 5. Read More

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September 2021

Unique insights into photocatalytic VOCs oxidation over WO/carbon dots nanohybrids assisted by water activation and electron transfer at interfaces.

J Hazard Mater 2021 Sep 10;423(Pt B):127134. Epub 2021 Sep 10.

Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Institute of Atmospheric Sciences, Fudan University, Shanghai 200433, PR China. Electronic address:

Internal electric field (IEF) at heterojunction interfaces can separate photoexcited charge carriers and promote photocatalytic performance. Here we have modified WO nanoplates with carbon dots (CDs) and constructed an interfacial IEF directing from CDs to WO with assistance of their remarkably different work functions. Such electric field drove photoexcited electrons to transport towards CDs and retained photoexcited holes to stay at WO, achieving electron/hole spatial separation. Read More

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September 2021

Saccharomyces cerevisiae Fpr1 functions as a chaperone to inhibit protein aggregation.

Int J Biol Macromol 2021 Sep 14. Epub 2021 Sep 14.

Department of Biotechnology, National Institute of Pharmaceutical Education and Research, Sector 67, S.A.S. Nagar, Punjab 160062, India. Electronic address:

Peptidyl prolyl isomerases (PPIases) accelerate the rate limiting step of protein folding by catalyzing cis/trans isomerization of peptidyl prolyl bonds. The larger PPIases have been shown to be multi-domain proteins, with functions other than isomerization of the proline-containing peptide bond. Recently, a few smaller PPIases have also been described for their ability to stabilize folding intermediates. Read More

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September 2021

Broad cross-reactivity across sarbecoviruses exhibited by a subset of COVID-19 donor-derived neutralizing antibodies.

Cell Rep 2021 Sep 8:109760. Epub 2021 Sep 8.

Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA. Electronic address:

Many anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) neutralizing antibodies target the angiotensin-converting enzyme 2 (ACE2) binding site on viral spike receptor-binding domains (RBDs). Potent antibodies recognize exposed variable epitopes, often rendering them ineffective against other sarbecoviruses and SARS-CoV-2 variants. Class 4 anti-RBD antibodies against a less-exposed, but more-conserved, cryptic epitope could recognize newly emergent zoonotic sarbecoviruses and variants, but they usually show only weak neutralization potencies. Read More

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September 2021

Biocatalytic, Intermolecular C-H Bond Functionalization for the Synthesis of Enantioenriched Amides.

Angew Chem Int Ed Engl 2021 Sep 17. Epub 2021 Sep 17.

California Institute of Technology, Department of Chemistry and Chemical Engineering, 1200 California Blvd., MC 210-41, 91125, Pasadena, UNITED STATES.

Directed evolution of heme proteins has opened access to new-to-nature enzymatic activity that can be harnessed to tackle synthetic challenges. Among these, reactions resulting from active site iron-nitrenoid intermediates present a powerful strategy to forge C-N bonds with high site- and stereoselectivity. Here we report a biocatalytic, intermolecular benzylic C-H amidation reaction operating at mild and scalable conditions. Read More

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September 2021

Dual Iron Sites in Activation of N by Iron-Sulfur Cluster Anions FeS and FeS.

J Phys Chem Lett 2021 Sep 17:9269-9274. Epub 2021 Sep 17.

State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China.

Inspired by the fact that the active centers of natural nitrogenases are polynuclear iron-sulfur clusters, the reactivity of isolated iron-sulfur clusters toward N has received considerable attention to gain fundamental insights into the activation of the N≡N triple bond. Herein, a series of gas-phase iron-sulfur cluster anions FeS ( = 1-8, 0-) were prepared and their reactivities toward N were investigated systematically by mass spectrometry. Among the 44 investigated clusters, only FeS and FeS showed superior reactivity toward N. Read More

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September 2021

Crucial Role of Conjugation in Monolayer-Protected Metal Clusters with Aromatic Ligands: Insights from the Archetypal AuL Cluster Compounds.

J Phys Chem Lett 2021 Sep 17:9262-9268. Epub 2021 Sep 17.

Aix-Marseille University, CNRS, CINAM, Marseille 13288, France.

Ligand-protected metal clusters are employed in a great many applications that include notably energy conversion and biomedical uses. The interaction between the ligands and the metallic cores, mediated by an often complex interface, profoundly influences the properties of small clusters, in particular. Nonetheless, the mechanisms of interaction remain far from fully understood. Read More

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September 2021

Skeleton Reorganization of Substituted Benzocyclobutenols through Rh-Catalyzed C-C Bond Cleavage Manipulated by Hydrogen Transfer.

Org Lett 2021 Sep 17. Epub 2021 Sep 17.

Department of Chemistry, Fudan University, Shanghai 200433, P. R. China.

Although transition-metal-catalyzed C-C bond activation has been investigated extensively, C-C bond cleavage manipulated by hydrogen transfer has been unexplored. In this work, we disclose a skeleton reorganization of alkene-tethered benzocyclobutenols through Rh-catalyzed C-C bond cleavage coupled with intra- and intermolecular hydrogen transfer. The reaction pathway was well-tuned by the catalytic systems. Read More

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September 2021

Modeling Liquid Water by Climbing up Jacob's Ladder in Density Functional Theory Facilitated by Using Deep Neural Network Potentials.

J Phys Chem B 2021 Sep 17. Epub 2021 Sep 17.

Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, United States.

Within the framework of Kohn-Sham density functional theory (DFT), the ability to provide good predictions of water properties by employing a strongly constrained and appropriately normed (SCAN) functional has been extensively demonstrated in recent years. Here, we further advance the modeling of water by building a more accurate model on the fourth rung of Jacob's ladder with the hybrid functional, SCAN0. In particular, we carry out both classical and Feynman path-integral molecular dynamics calculations of water with the SCAN0 functional and the isobaric-isothermal ensemble. Read More

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September 2021

A Novel Tin-Bonded Silicon Anode for Lithium-Ion Batteries.

ACS Appl Mater Interfaces 2021 Sep 17. Epub 2021 Sep 17.

State Key Laboratory of Silicon Materials and School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China.

Poor cyclic stability and low rate performance due to dramatic volume change and low intrinsic electronic conductivity are the two key issues needing to be urgently solved in silicon (Si)-based anodes for lithium-ion batteries. Herein, a novel tin (Sn)-bonded Si anode is proposed for the first time. Sn, which has a high electronic conductivity, is used to bond the Si-anode material and copper (Cu) current collector together using a hot-pressed method with a temperature slightly above the melting point of Sn. Read More

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September 2021

gem-Heteroatom-substituted fluoroalkenes as mimics of amide derivatives or phosphates: a comprehensive review.

Chemistry 2021 Sep 17. Epub 2021 Sep 17.

INSA Rouen Normandie, UMR 6014 COBRA, 1 rue tesnière, 76821, Mont-Saint-Aignan, FRANCE.

gem -Heteroatom-substituted fluoroalkenes have received little attention despite their great potential in medicinal chemistry or in fine chemistry. Indeed, due to the electronic and steric similarity between fluoroalkene moiety and amide bond as well as the high strength of carbon-fluorine bond, these gem -heteroatom-substituted fluoroalkenes could be envisioned as stable mimics of various important organic functions such as phosphates, carbamates, S-thiocarbamates and ureas. We present herein an overview describing the syntheses over the last decade of heteroatom-substituted fluoroalkenes in geminal position. Read More

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September 2021

Multi-photoresponsive triphenylethylene derivatives with photochromism, photodeformation and room temperature phosphorescence.

Mater Horiz 2021 Sep 17. Epub 2021 Sep 17.

Hubei Key Lab on Organic and Polymeric Opto-Electronic Materials, Sauvage Center for Molecular Sciences, Department of Chemistry, Wuhan University, Wuhan 430072, China.

A series of triphenylethylene derivatives exhibited multi-photoresponsive properties, including photochromism, photodeformation and room temperature phosphorescence (RTP), which are strongly related to molecular conformations and packing in the aggregated states. Accordingly, these properties can be subtly adjusted by substituents to the center double bond and/or peripheral phenyl moieties. The introduction of bromine atom was beneficial to photochromism and photodeformation properties as a result of the additional C-H⋯Br interactions and electron-withdrawing property. Read More

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September 2021

Interactions study of 1,2,4-triazole derivatives in acid medium using molecular dynamics.

Authors:
Radia Mahboub

J Biomol Struct Dyn 2021 Sep 17:1-10. Epub 2021 Sep 17.

Department of Chemistry, Faculty of Sciences, University of Tlemcen, Tlemcen, Algeria.

We investigated the interaction of some 1,2,4-triazoles derivatives: 4-amino-3-methylthio-5-phenyl-4-1,2,4-triazole , 4-amino-5-phenyl-4-1,2,4-triazole-3-thiol , 4-amino-5-phenyl-2-1,2,4-triazole-3-thione , and 4-amino-5-phenyl-4-1,2,4-triazole-3-thiol (respectively ) using the molecular dynamics simulation. First, we employed this method to predict the total energies in vacuum and in solutions (water and acid media). Then, we calculated the MD parameters: interaction energies and angle parameters. Read More

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September 2021

Nickel(II)-Catalyzed [3 + 2] Cycloaddition of Nitrones and Allenoates to Access -Vinylindoles and -Vinylpyrroles.

Org Lett 2021 Sep 17. Epub 2021 Sep 17.

State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Collaborative Innovation Center for Guangxi Ethnic Medicine; School of Chemistry and Pharmaceutical Sciences, Guangxi Normal University, 15 Yu Cai Road, Guilin 541004, China.

A variety of -vinylindoles and -vinylpyrroles were prepared in moderate to good yields through the nickel(II)-catalyzed [3 + 2] cycloaddition of α,β-unsaturated nitrones with allenoates under mild reaction conditions. A rational mechanism for the formation of -vinylindoles was proposed based on the O-labeled experiments and key intermediates detected by high-resolution mass spectrometry trace experiments. The present method highlights a nickel(II)-controlled cyclization, atom-economical reaction, broad substrate scope, good functional group tolerance, and high Z-stereoselectivity for the enamine bond. Read More

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September 2021

Synergistic effects of Co/CoO nanoparticles on imine-based covalent organic frameworks for enhanced OER performance.

Nanoscale 2021 Sep 17;13(35):14854-14865. Epub 2021 Sep 17.

Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, College of Environmental and Chemical Engineering, Shanghai University of Electric Power, Shanghai 200090, China.

The development of non-noble metal electrocatalysts toward the oxygen evolution reaction (OER) is a key challenge in advancing electrocatalytic water splitting, which is essential for the commercialization of clean and renewable energy. A covalent organic framework (COF) has a precise and controllable structure, high π-π conjugation, large surface area, and porosity and shows great potential as an OER electrocatalyst. However, the relative conductivity and inherent instability greatly limit the further improvement of its performance. Read More

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September 2021

Caged structural water molecules emit tunable brighter colors by topological excitation.

Nanoscale 2021 Sep 17;13(35):15058-15066. Epub 2021 Sep 17.

Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Laboratory of Interface and Water Science, College of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China.

Intrinsically, free water molecules are a colourless liquid. If it is colourful, why and how does it emit the bright colours? We provided direct evidence that when water was trapped into the sub-nanospace of zeolites, the structural water molecules (SWs) exhibited strong tunable photoluminescence (PL) emissions from blue to red colours with unprecedented ultra-long lifetimes up to the second scale at liquid nitrogen temperature. Further controlled experiments and combined characterizations by time-resolved steady-state and ultra-fast femtosecond (fs) transient optical spectroscopy showed that the singly adsorbed hydrated hydroxide complex {OH·HO} as SWs in the confined nanocavity is the true emitter centre, whose PL efficiency strongly depends on the type and stability of the SWs, which is dominated by H-bond interactions, such as the solvent effect, pH value and operating temperature. Read More

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September 2021

Ternary supramolecular nanocomplexes for superior anticancer efficacy of natural medicines.

Nanoscale 2021 Sep 17;13(35):15085-15099. Epub 2021 Sep 17.

Chongqing Research Center for Pharmaceutical Engineering, School of Pharmacy, Chongqing Medical University, Chongqing 400016, China.

The discovery of effective anticancer drug delivery systems and elucidation of the mechanism are enormous challenges. Using two drug administration-approved biomaterials, we constructed a natural medicine (NM)-loaded ternary supramolecular nanocomplex (TSN) suitable for large-scale production. The TSN has a better effect against cancer cells/stem cells than NM with differentially upregulated (27 59) and downregulated (165 66) proteins, respectively. Read More

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September 2021

Synthesis of axially chiral biaryl thioglycosides through thiosugar-directed Pd-catalyzed asymmetric C-H activation.

Chem Commun (Camb) 2021 Sep 17. Epub 2021 Sep 17.

Université Paris-Saclay, CNRS, BioCIS, 92290, Châtenay-Malabry, France.

Herein we report for the first time that the thiosugar moiety can be used both as a directing group enabling the regioselective activation of a C-H bond of biaryl scaffolds and as a chiral source inducing axial chirality. Our approach enables the easy generation of complex thioglycoside atropoisomers, thus paving the way to new products of potential biological interest. Read More

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September 2021

Identification of novel potential inhibitors of varicella-zoster virus thymidine kinase from ethnopharmacologic relevant plants through an approach.

J Biomol Struct Dyn 2021 Sep 17:1-16. Epub 2021 Sep 17.

Department of Biochemistry, School of Biological Sciences, University of Cape Coast, Cape Coast, Ghana.

Although Varicella or chickenpox infection which is caused by the varicella-zoster virus (VZV) has significantly been managed through vaccination, it remains an infection that poses threats to the nearest future due to therapeutic drawbacks. The focus of this research was geared towards screening for the identification of novel compounds in plants of ethnopharmacological relevance in the treatment of chicken pox in West Africa. The work evaluated 65 compounds reported to be present in and to identify potential inhibitors of thymidine kinase, the primary drug target of varicella zoster virus. Read More

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September 2021