Search results for "Quinone"
showing 10 items of 315 documents
Geldanamycin and its derivatives as Hsp90 inhibitors
2012
The Hsp90 molecule, one of the most abundant heat shock proteins in mammalian cells, maintains homeostasis and prevents stress-induced cellular damage. Hsp90 is expressed under normal conditions at a level of about 1-2 Percent of total proteins, while its expression increases 2-10 fold in cancer cells. The two main constitutively expressed isoforms of Hsp90 are known as Hsp90-alpha and Hsp90-beta, and their upregulation is associated with tumor progression, invasion and formation of metastases, as well as development of drug resistance. The Hsp90 is a key target for many newly established, potent anticancer agents containing Hsp90 N-terminal ATP binding inhibitors, such as geldanamycin, and…
Novel Alkylanthracenes Synthesis, Reductive Alkylation, and Reductive Polymerization
1988
A series of novel substituted anthracenes has been prepared which carry two or four n-alkyl groups at C-2 and C-3 (C-6 and C-7). The route taken includes the synthesis of novel 2,3-dialkylbutadienes, their Diels-Alder reaction with 1,4-benzo- or 1,4-naphthoquinone, the dehydrogenation of the adducts, and the reduction of the anthraquinones. The substituted anthracenes are submitted to reduction and reductive alkylation in ethereal solvents and in liquid ammonia to yield 9,10-dialkyl-substituted 9,10-dihydroanthracenes. A modification of the reductive alkylation, i.e. the introduction of 1,n-dihaloalkanes as electrophiles, provides polymeric chains, in which dihydroanthracene moieties are li…
Tuning Reductive and Oxidative Photoinduced Electron Transfer in Amide‐Linked Anthraquinone–Porphyrin–Ferrocene Architectures
2014
Porphyrin amino acids 3a–3h with meso substituents Ar of tunable electron-donating power (Ar = 4-C6H4OnBu, 4-C6H4OMe, 4-C6H4Me, Mes, C6H5, 4-C6H4F, 4-C6H4CF3, C6F5) have been linked at the N terminus to anthraquinone Q as electron acceptor through amide bonds to give Q-PAr dyads 4a–4h. These were conjugated to ferrocene Fc at the C terminus as electron donor to give the acceptor-chromophore-donor Q-PAr-Fc triads 6a–6h. To further modify the energies of the electronically excited and charge-separated states, the triads 6a–6h were metallated with zinc(II) to give the corresponding Q-(Zn)PAr-Fc triads Zn-6a–Zn-6h. The Q-PAr1 dyad (Ar1 = C6H5) was further extended with a second porphyrin PAr2 (…
Photochemie elektronenreicher 1,3‐Distyrylbenzole
1988
Die 1,3-Distyrylbenzole 3 mit bis zu sieben Alkoxygruppen werden der oxidativen Photocyclisierung unterworfen. Bei der Bildung der Produkte 6, 7 und 8 konnen als Konkurrenz- bzw. Folgeprozesse die Abspaltung von Methanol (3bb 7bb, 3bf 7bf) und die Chinonoxidation (3cf 8) auftreten. Die eigensensiblisierte Erzeugung von Singulettsauerstoff kann bei 6bf zur Endoperoxidbildung fuhren (6bf 11). Photochemistry of Electron-Rich 1,3-Distyrylbenzenes The 1,3-distyrylbenzenes 3, containing up to seven alkoxy groups, are subjected to the oxidative photocyclization. Elimination of methanol (3bb 7bb, 3bf 7bf) and quinone oxidation can occur as competitive or consecutive reactons in the formation of the…
The oxidation of ubiquinol by the isolated rieske iron-sulfur protein in solution
1990
The pre-steady-state redox reactions of the Rieske iron-sulfur protein isolated from beef heart mitochondria have been characterized. The rates of oxidation by c-type cytochromes is much faster than the rate of reduction by ubiquinols. This enables the monitoring of the oxidation of ubiquinols by the Rieske protein through the steady-state electron transfer to cytochrome c in solution. The pH and ionic strength dependence of this reaction indicate that the ubiquinol anion is the direct reductant of the oxidized cluster of the iron-sulfur protein. The second electron from ubiquinol is diverted to oxygen by the isolated Rieske protein, and forms oxygen radicals that contribute to the steady-s…
Rapid and Complete Surface Modification with Strain-Promoted Oxidation-Controlled Cyclooctyne-1,2-Quinone Cycloaddition (SPOCQ)
2017
Abstract Strain‐promoted oxidation‐controlled cyclooctyne‐1,2‐quinone cycloaddition (SPOCQ) between functionalized bicyclo[6.1.0]non‐4‐yne (BCN) and surface‐bound quinones revealed an unprecedented 100 % conjugation efficiency. In addition, monitoring by direct analysis in real time mass spectrometry (DART‐MS) revealed the underlying kinetics and activation parameters of this immobilization process in dependence on its microenvironment.
Strain-Promoted Cycloaddition of Cyclopropenes with o-Quinones : A Rapid Click Reaction
2018
Abstract Novel click reactions are of continued interest in fields as diverse as bio‐conjugation, polymer science and surface chemistry. Qualification as a proper “click” reaction requires stringent criteria, including fast kinetics and high conversion, to be met. Herein, we report a novel strain‐promoted cycloaddition between cyclopropenes and o‐quinones in solution and on a surface. We demonstrate the “click character” of the reaction in solution and on surfaces for both monolayer and polymer brush functionalization.
Thermal expansion and magnetic properties of benzoquinone-bridged dinuclear rare-earth complexes.
2017
The synthesis and structural characterization of two benzoquinone-bridged dinuclear rare-earth complexes [BQ(MCl2·THF3)2] (BQ = 2,5-bisoxide-1,4-benzoquinone; M = Y (1), Dy (2)) are described. Of these reported metal complexes, the dysprosium analogue 2 is the first discrete bridged dinuclear lanthanide complex in which both metal centres reside in pentagonal bipyramidal environments. Interestingly, both complexes undergo significant thermal expansion upon heating from 120 K to 293 K as illustrated by single-crystal X-ray and powder diffraction experiments. AC magnetic susceptibility measurements reveal that 2 does not show the slow relation of magnetization in zero dc field. The absent of …
Effects of caffeoyl conjugates of isoprenyl-hydroquinone glucoside and quinic acid on leukocyte function.
2002
The activity of three prenylhydroquinone glucosides (1-3) and four caffeoylquinic esters (4-7), obtained from Phagnalon rupestre, on elastase release, myeloperoxidase activity and superoxide and leukotriene B(4) production from polymorphonuclear leukocytes was determined. 4,5-Dicaffeoylquinic acid strongly inhibited elastase release with an IC(50) value of 4.8 microM. Methylated caffeoylquinic derivatives were the most potent inhibitors of myeloperoxidase (IC(50) near 60 microM), whereas both methylated and free carboxyl isomers inhibited superoxide production with similar potency (IC(50) between 27 and 42 microM). The monocaffeoyl conjugate of prenylhydroquinone glucoside (3), the most pot…
Identification of HSP90 as a new GABARAPL1 (GEC1)-interacting protein
2011
GABARAPL1 belongs to the small family of GABARAP proteins (including GABARAP, GABARAPL1 and GABARAPL2/GATE-16), one of the two subfamilies of the yeast Atg8 orthologue. GABARAPL1 is involved in the intracellular transport of receptors, via an interaction with tubulin and GABA(A) or kappa opioid receptors, and also participates in autophagy and cell proliferation. In the present study, we identify the HSP90 protein as a novel interaction partner for GABARAPL1 using GST pull-down, mass spectrometry and coimmunoprecipitation experiments. GABARAPL1 and HSP90 partially colocalize in MCF-7 breast cancer cells overexpressed Dsred-GABARAPL1 and in rat brain. Moreover, treatment of MCF-7 cells overe…