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21.
Mario Caruana Angelique Camilleri Maria Ylenia Farrugia Stephanie Ghio Michaela Jakubí
kov Ruben J. Cauchi Neville Vassallo 《Molecules (Basel, Switzerland)》2021,26(5)
The identification of compounds which protect the double-membrane of mitochondrial organelles from disruption by toxic confomers of amyloid proteins may offer a therapeutic strategy to combat human neurodegenerative diseases. Here, we exploited an extract from the marine brown seaweed Padina pavonica (PPE) as a vital source of natural bioactive compounds to protect mitochondrial membranes against insult by oligomeric aggregates of the amyloidogenic proteins amyloid-β (Aβ), α-synuclein (α-syn) and tau, which are currently considered to be major targets for drug discovery in Alzheimer’s disease (AD) and Parkinson’s disease (PD). We show that PPE manifested a significant inhibitory effect against swelling of isolated mitochondria exposed to the amyloid oligomers, and attenuated the release of cytochrome c from the mitochondria. Using cardiolipin-enriched synthetic lipid membranes, we also show that dye leakage from fluorophore-loaded vesicles and formation of channel-like pores in planar bilayer membranes are largely prevented by incubating the oligomeric aggregates with PPE. Lastly, we demonstrate that PPE curtails the ability of Aβ42 and α-syn monomers to self-assemble into larger β-aggregate structures, as well as potently disrupts their respective amyloid fibrils. In conclusion, the mito-protective and anti-aggregator biological activities of Padina pavonica extract may be of therapeutic value in neurodegenerative proteinopathies, such as AD and PD. 相似文献
22.
Rouven F. Pfleger Sören Schlittenhardt Dr. Marcel P. Merkel Prof. Dr. Mario Ruben Prof. Dr. Karin Fink Dr. Christopher E. Anson Prof. Jesper Bendix Prof. Dr. Annie K. Powell 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(61):15086-15095
We report three structurally related single ion Dy compounds using the pentadentate ligand 2,6-bis((E)-1-(2-(pyridin-2-yl)-hydrazineylidene)ethyl)pyridine (H2dapp) [Dy(H2dapp)(NO3)2]NO3 ( 1 ), [Dy(H2dapp)(OAc)2]Cl ( 2 ) and [Dy(H2dapp)(NO3)2]Cl0.92(NO3)0.08 ( 3 ). The (H2dapp) occupies a helical twisted pentagonal equatorial arrangement with two anionic ligands in the axial positions. Further influence on the electronic and magnetic structure is provided by a closely associated counterion interacting with the central N−H group of the (H2dapp). The slow relaxation of the magnetisation shows that the anionic acetates give the greatest slowing down of the magnetisation reversal. Further influence on the relaxation properties of compounds 1 and 2 is the presence of short nitrate-nitrate intermolecular ligand contact opening further lattice relaxation pathways. 相似文献
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Metal‐Catalyzed Reductive Coupling Reactions of Organic Halides with Carbonyl‐Type Compounds 下载免费PDF全文
Dr. Toni Moragas Dr. Arkaitz Correa Prof. Dr. Ruben Martin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(27):8242-8258
Metal‐catalyzed reductive coupling reactions of aryl halides and (pseudo)halides with carbonyl‐type compounds have undergone an impressive development within the last years. These methodologies have shown to be a powerful alternate strategy, practicality aside, to the use of stoichiometric, well‐defined, and, in some cases, air‐sensitive organometallic species. In this Minireview, the recent findings in this field are summarized, with particular emphasis on the mechanistic interpretation of the results and future aspects of this area of expertise. 相似文献
24.
Complex Surface Chemistry of an Otherwise Inert Solvent Molecule: Tetrahydrofuran on Si(001) 下载免费PDF全文
Dr. Gerson Mette Marcel Reutzel Dr. Ruben Bartholomäus Dr. Slimane Laref Dr. Ralf Tonner Prof. Dr. Michael Dürr Prof. Dr. Ulrich Koert Prof. Dr. Ulrich Höfer 《Chemphyschem》2014,15(17):3725-3728
The reaction of tetrahydrofuran (THF), an otherwise inert solvent molecule, on Si(001) was experimentally studied in ultra‐high vacuum. Using scanning tunneling microscopy (STM) and photoelectron spectroscopy at variable temperature, we could both isolate a datively bound intermediate state of THF on Si(001), as well as the final configuration that bridges two dimer rows of the Si(001) surface after ether cleavage. The latter configuration implies splitting of the O?C bond, which is typically kinetically suppressed. THF thus exhibits a hitherto unknown reactivity on Si(001). 相似文献
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26.
Ruben Elvas-Leito Filomena Martins Leonor Borbinha Catarina Marranita Angela Martins Nelson Nunes 《Molecules (Basel, Switzerland)》2020,25(23)
Attempts to optimize heterogeneous catalysis often lack quantitative comparative analysis. The use of kinetic modelling leads to rate (k) and relative sorption equilibrium constants (K), which can be further rationalized using Quantitative Structure-Property Relationships (QSPR) based on Multiple Linear Regressions (MLR). Friedel-Crafts acylation using commercial and hierarchical BEA zeolites as heterogeneous catalysts, acetic anhydride as the acylating agent, and a set of seven substrates with different sizes and chemical functionalities were herein studied. Catalytic results were correlated with the physicochemical properties of substrates and catalysts. From this analysis, a robust set of equations was obtained allowing inferences about the dominant factors governing the processes. Not entirely surprising, the rate and sorption equilibrium constants were found to be explained in part by common factors but of opposite signs: higher and stronger adsorption forces increase reaction rates, but they also make the zeolite active sites less accessible to new reactant molecules. The most relevant parameters are related to the substrates’ molecular size, which can be associated with different reaction steps, namely accessibility to micropores, diffusion capacity, and polarizability of molecules. The relatively large set of substrates used here reinforces previous findings and brings further insights into the factors that hamper/speed up Friedel-Crafts reactions in heterogeneous media. 相似文献
27.
Ruben Canton‐Vitoria Tobias Scharl Anastasios Stergiou Alejandro Cadranel Raul Arenal Dirk M. Guldi Nikos Tagmatarchis 《Angewandte Chemie (International ed. in English)》2020,59(10):3976-3981
Molybdenum disulfide nanosheets covalently modified with porphyrin were prepared and fully characterized. Neither the porphyrin absorption nor its fluorescence was notably affected by covalent linkage to MoS2. The use of transient absorption spectroscopy showed that a complex ping‐pong energy‐transfer mechanism, namely from the porphyrin to MoS2 and back to the porphyrin, operated. This study reveals the potential of transition‐metal dichalcogenides in photosensitization processes. 相似文献
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30.
A method is described to couple sterically-hindered electron-poor anilines to the 4-position of the pyrimidine core using a pyrimidine-2,4-bis(trifluoromethanesulfonate). 相似文献