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941.
Maxim E. Kukushkin Dmitriy A. Skvortsov Marina A. Kalinina Viktor A. Tafeenko Vladimir V. Burmistrov Gennady M. Butov 《Phosphorus, sulfur, and silicon and the related elements》2020,195(7):544-555
AbstractAn effective and highly regio- and diastereoselective one-pot synthesis of two types of dispiro heterocyclic systems (2-thioxodispiro[imidazolidine-4,3′-pyrrolidine-2′,3″-indoline]-2″,5-diones and 2-thioxodispiro[imidazolidine-4,3′-pyrrolidine-4′,3″-indoline]-2″,5-diones) comprising pyrrolidinyl-oxindole, thiohydantoin and adamantane moieties has been developed based on a 1,3-dipolar cycloaddition of azomethine ylides, generated from isatin and sarcosine or formaldehyde and sarcosine, to adamantane-containing electron-deficient alkenes. Several molecules have demonstrated a considerable cytotoxicity against A549, HEK293T, MCF7 and VA13 cancer cell lines. The possible mechanism of anticancer activity of the synthesized compounds based on literature data may be the inhibition of p53/MDM2 interaction; however, we did not observe significant p53 activation using a reporter construction in A549 cell line in the relevant concentration range. 相似文献
942.
943.
Khouloud Dammak Marina Porchia Michele De Franco Mirella Zancato Houcine Naïli Valentina Gandin Cristina Marzano 《Molecules (Basel, Switzerland)》2020,25(22)
A series of neutral mixed-ligand [HB(pz)3]Ag(PR3) silver(I) complexes (PR3 = tertiary phosphine, [HB(pz)3]− = tris(pyrazolyl)borate anion), and the corresponding homoleptic [Ag(PR3)4]BF4 compounds have been synthesized and fully characterized. Silver compounds were screened for their antiproliferative activities against a wide panel of human cancer cells derived from solid tumors and endowed with different platinum drug sensitivity. Mixed-ligand complexes were generally more effective than the corresponding homoleptic derivatives, but the most active compounds were [HB(pz)3]Ag(PPh3) (5) and [Ag(PPh3)4]BF4 (10), both comprising the lipophilic PPh3 phosphine ligand. Detailed mechanistic studies revealed that both homoleptic and heteroleptic silver complexes strongly and selectively inhibit the selenoenzyme thioredoxin reductase both as isolated enzyme and in human ovarian cancer cells (half inhibition concentration values in the nanomolar range) causing the disruption of cellular thiol-redox homeostasis, and leading to apoptotic cell death. Moreover, for heteroleptic Ag(I) derivatives, an additional ability to damage nuclear DNA has been detected. These results confirm the importance of the type of silver ion coordinating ligands in affecting the biological behavior of the overall corresponding silver complexes, besides in terms of hydrophilic–lipophilic balance, also in terms of biological mechanism of action, such as interaction with DNA and/or thioredoxin reductase. 相似文献
944.
Mirit Kolet Melad Atrash Karen Molina Daniel Zerbib Yael Albo Faina Nakonechny Marina Nisnevitch 《Molecules (Basel, Switzerland)》2020,25(24)
Replacing fossil fuels with biodiesel enables the emission of greenhouse gases to be decreased and reduces dependence on fossil fuels in countries with poor natural resources. Biodiesel can be produced by an esterification reaction between free fatty acids (FFAs) and methanol or by transesterification of triglycerides from oils. Both reactions require homogeneous or heterogeneous catalysis. Production of biodiesel catalyzed by heterogeneous catalysts seems to be the preferred route, enabling easy product separation. As we have previously shown, the Lewis acids AlCl3 and BF3 can serve as highly efficient catalysts under ultrasonic activation. The present study focused on the development of oleic acid (OA) esterification with methanol by the same catalysts immobilized in silica matrices using the sol–gel synthesis route. During the course of immobilization, AlCl3 converts to AlCl3 × 6H2O (aluminite) and BF3 is hydrolyzed with the production of B2O3. The immobilized catalysts can be reused or involved in a continuous process. The possibility of biodiesel production using immobilized catalysts under ultrasonic activation is shown for the conversion of FFAs into biodiesel in batch and continuous mode. 相似文献
945.
Andreas Meyer Sebastian Dechert Surjendu Dey Claudia Hbartner Marina Bennati 《Angewandte Chemie (International ed. in English)》2020,59(1):373-379
Spectroscopic and biophysical methods for structural determination at atomic resolution are fundamental in studies of biological function. Here we introduce an approach to measure molecular distances in bio‐macromolecules using 19F nuclear spins and nitroxide radicals in combination with high‐frequency (94 GHz/3.4 T) electron–nuclear double resonance (ENDOR). The small size and large gyromagnetic ratio of the 19F label enables to access distances up to about 1.5 nm with an accuracy of 0.1–1 Å. The experiment is not limited by the size of the bio‐macromolecule. Performance is illustrated on synthesized fluorinated model compounds as well as spin‐labelled RNA duplexes. The results demonstrate that our simple but strategic spin‐labelling procedure combined with state‐of‐the‐art spectroscopy accesses a distance range crucial to elucidate active sites of nucleic acids or proteins in the solution state. 相似文献
946.
Igor Krivtsov Dariusz Mitoraj Christiane Adler Marina Ilkaeva Mariana Sardo Luís Mafra Christof Neumann Andrey Turchanin Chunyu Li Benjamin Dietzek Robert Leiter Johannes Biskupek Ute Kaiser Changbin Im Bjrn Kirchhoff Timo Jacob Radim Beranek 《Angewandte Chemie (International ed. in English)》2020,59(1):487-495
Heptazine‐based polymeric carbon nitrides (PCN) are promising photocatalysts for light‐driven redox transformations. However, their activity is hampered by low surface area resulting in low concentration of accessible active sites. Herein, we report a bottom‐up preparation of PCN nanoparticles with a narrow size distribution (ca. 10±3 nm), which are fully soluble in water showing no gelation or precipitation over several months. They allow photocatalysis to be carried out under quasi‐homogeneous conditions. The superior performance of water‐soluble PCN, compared to conventional solid PCN, is shown in photocatalytic H2O2 production via reduction of oxygen accompanied by highly selective photooxidation of 4‐methoxybenzyl alcohol and benzyl alcohol or lignocellulose‐derived feedstock (ethanol, glycerol, glucose). The dissolved photocatalyst can be easily recovered and re‐dissolved by simple modulation of the ionic strength of the medium, without any loss of activity and selectivity. 相似文献
947.
Gisselle R. Apud Pedro A. Aredes-Fernández Marina Kritsanida Raphael Grougnet 《Natural product research》2020,34(18):2656-2659
AbstractTwenty four extracts from Bignoniaceae plants of northwest Argentina were tested for antifungal activity against Aspergillus species responsible of the grape black rot. Stems and leaves of Amphilophium cynanchoides, Macfadyena cynanchoides, Tecoma stans and Jacaranda mimosifolia were separately extracted with solvents of increasing polarity to obtain the dichloromethane (fCH2Cl2), ethyl acetate (fEtOAc) and methanol extracts (fMeOH). The fCH2Cl2 from stem of M. cynanchoides had the lowest IC50 (1.0–1.2?mg/mL) and MID values (0.6–1.2?mg) and the highest ID values (5.0–6.8?mm) on A. niger and A. carbonarius. The main contributors of the antifungal activity of fCH2Cl2 were identified as lapachol (MIC?=?0.25–1.00?mg/ml) and 1-hydroxy-4-methylanthraquinone (MIC?=?0.0625–0.125?mg/mL). These compounds synergized the antifungal activity of sodium metabisulfite and showed an additive effect in mixtures with propiconazol. They might be used as additives of commercial antifungals to protect grapes against A. niger and A. carbonarius. 相似文献
948.
Andreas Reif Sebastian Siebenhaar Andrea Tröster Marina Schmälzlein Carolin Lechner Phanindra Velisetty Karen Gottwald Claudia Pöhner Irene Boos Volker Schubert Prof. Stefan Rose‐John Prof. Carlo Unverzagt 《Angewandte Chemie (International ed. in English)》2014,53(45):12125-12131
Human interleukin 6 (IL‐6) is a potent cytokine with immunomodulatory properties. As the influence of N‐glycosylation on the in vivo activities of IL‐6 could not be elucidated so far, a semisynthesis of homogeneous glycoforms of IL‐6 was established by sequential native chemical ligation. The four cysteines of IL‐6 are convenient for ligations and require only the short synthetic glycopeptide 43–48. The Cys‐peptide 49–183 could be obtained recombinantly by cleavage of a SUMO tag. The fragment 1–42 was accessible by the simultaneous cleavage of two inteins, leading to the 1–42 thioester with the native N‐terminus. Ligation and refolding studies showed that the inherently labile Asp? Pro bond 139–140 was detrimental for the sequential C‐ to N‐terminal ligation. A reversed ligation sequence using glycopeptide hydrazides gave full‐length IL‐6 glycoproteins, which showed full bioactivity after efficient refolding and purification. 相似文献
949.
Supramolecular Engineering of Oligothiophene Nanorods without Insulators: Hierarchical Association of Rosettes and Photovoltaic Properties 下载免费PDF全文
Prof. Dr. Shiki Yagai Mika Suzuki Dr. Xu Lin Marina Gushiken Takuya Noguchi Prof. Dr. Takashi Karatsu Prof. Dr. Akihide Kitamura Prof. Dr. Akinori Saeki Prof. Dr. Shu Seki Dr. Yoshihiro Kikkawa Yuki Tani Prof. Dr. Ken‐ichi Nakayama 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(49):16128-16137
Supramolecular rosettes of oligothiophenes that do not bear long aliphatic tails have been designed as semiconducting nanomaterials for solution‐processable bulk heterojunction solar cells. The rosettes consist of six barbiturated thienyl[oligo(hexylthiophene)] units (Bar‐T‐hTn; n=3,4,5) aggregated by multiple hydrogen bonds, which have been directly visualized by scanning tunneling microscopy (STM) at a solid–liquid interface. 1H NMR spectroscopy in [D8]toluene showed that Bar‐T‐hTn exists as a mixture of monomers and small hydrogen‐bonded aggregates. Hierarchical organization of the hydrogen‐bonded aggregates took place through π–π stacking interactions upon casting their toluene solutions, resulting in the growth of highly ordered nanorods whose widths are consistent with the diameters of the rosettes. The nanorods could be generated in the presence of soluble fullerene derivatives via solution casting or the annealing of the resulting thin films. The solar cells fabricated based on these bulk heterojunction films showed power conversion efficiencies of 1–3 %, which are far higher than those of the non‐hydrogen‐bonded reference oligothiophene and the derivative that possesses long aliphatic tails. 相似文献
950.
Gisele A. B. Canuto Emerson A. Castilho-Martins Marina F. M. Tavares Luis Rivas Coral Barbas Ángeles López-Gonzálvez 《Analytical and bioanalytical chemistry》2014,406(14):3459-3476
Miltefosine (MT) (hexadecylphosphocholine) was implemented to cope with resistance against antimonials, the classical treatment in Leishmaniasis. Given the scarcity of anti- Leishmania (L) drugs and the increasing appearance of resistance, there is an obvious need for understanding the mechanism of action and development of such resistance. Metabolomics is an increasingly popular tool in the life sciences due to it being a relatively fast and accurate technique that can be applied either with a particular focus or in a global manner to reveal new knowledge about biological systems. Three analytical platforms, gas chromatography (GC), liquid chromatography (LC) and capillary electrophoresis (CE) have been coupled to mass spectrometry (MS) to obtain a broad picture of metabolic changes in the parasite. Impairment of the polyamine metabolism from arginine (Arg) to trypanothione in susceptible parasites treated with MT was in some way expected, considering the reactive oxygen species (ROS) production described for MT. Importantly, in resistant parasites an increase in the levels of amino acids was the most outstanding feature, probably related to the adaptation of the resistant strain for its survival inside the parasitophorous vacuole. Online Abstract Figure
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