Search results for "Redox"

Erratum to “Cerium effect on the phase structure, phase stability and redox properties of Ce-doped strontium ferrates”

2008

Study of various indicating redox systems on the indirect flow-injection biamperometric determination of pharmaceuticals

1999

Abstract The reversible redox couples (Fe(III)/Fe(II); Ce(IV)/Ce(III); Fe(CN) 6 3– /Fe(CN) 6 4− ; I 2 /I − ; Br 2 /Br − and VO 3 − /VO 2+ ) were studied as indicating redox systems for biamperometric determination of paracetamol in a flow injection assembly. Considering the selectivity of assayed systems against excipients and antioxidants that typically are presented in pharmaceutical formulations (e.g. sucrose, glucose, ascorbic acid and hydrogen sulphite) the systems Fe(III)/Fe(II) and VO 3 − /VO 2+ were selected for the determination of the drug. The sample was injected into a carrier which merged with the oxidant stream where the drug was oxidised by excess oxidant. The observed signal…

The anion impact on the self-assembly of naphthalene diimide diimidazolium salts

2017

Naphthalene diimide diimidazolium salts differing in the anion nature were synthesized and their properties as well as their self-assembly behaviour were investigated. In particular, we took into consideration the N,N′-bis-(1-octyl-3-propylimidazolium)-naphthalene diimide cations and anions differing in size, shape and coordination abilities like [I−], [BF4−] and [NTf2−]. After determination of thermal behaviour, using differential scanning calorimetry and thermal gravimetric analysis, the electrochemical stability and redox properties were assessed using cyclic voltammetry. The self-assembly behaviour of the salts was investigated using concentration and temperature-dependent spectroscopic…

Spectral and structural insights of copper reduction pathways in the system of CuX2-R2S (X=Cl, Br; R=allyl, n-propyl)

2021

Abstract We have explored the behaviour of Cu(II)/Cu(I) redox couple in the system CuX2-R2S, X = Cl, Br; R = allyl, n-propyl, under anhydrous and anaerobic conditions, thus simulating the reduction half cycle in the copper catalyzed oxidation of thioethers. In doing so, the Cl−Br substitution was critical for tuning the reduction potentials, while the replacement of propyl group by allyl group supported the trapping of oxidation by-product, halogen molecules. It was therefore possible to use the spectrophotometric titration, thereby providing information on the distribution of complex species in acetonitrile solution. The study showed that the trinuclear mixed−valence copper (I-II-II) aggre…

Characterization of Hydrophilic Gold(I) N-Heterocyclic Carbene (NHC) Complexes as Potent TrxR Inhibitors Using Biochemical and Mass Spectrometric App…

2017

We report here on the synthesis of a series of mono-and dinuclear gold(I) complexes exhibiting sulfonated bis(NHC) ligands and novel hydroxylated mono(NHC) Au(I) compounds, which were also examined for their 'biological activities. Initial cell viability assays show strong antiproliferative activities of the hydroxylated mono(NHC) gold compounds (8 > 9 > 10) against 2008 human ovarian cancer cells even after 1 h incubation. In order to gain insight into the mechanism of biological action of the gold compounds, their effect on the pivotal cellular target seleno-enzyme thioredoxin reductase (TrxR), involved in the maintenance of intracellular redox balance, was investigated in depth. Th…

Regulation of Human Mitochondrial Aldehyde Dehydrogenase (ALDH-2) Activity by Electrophiles in Vitro

2011

Recently, mitochondrial aldehyde dehydrogenase (ALDH-2) was reported to reduce ischemic damage in an experimental myocardial infarction model. ALDH-2 activity is redox-sensitive. Therefore, we here compared effects of various electrophiles (organic nitrates, reactive fatty acid metabolites, or oxidants) on the activity of ALDH-2 with special emphasis on organic nitrate-induced inactivation of the enzyme, the biochemical correlate of nitrate tolerance. Recombinant human ALDH-2 was overexpressed in Escherichia coli; activity was determined with an HPLC-based assay, and reactive oxygen and nitrogen species formation was determined by chemiluminescence, fluorescence, protein tyrosine nitration,…

Dimerization of visinin-like protein 1 is regulated by oxidative stress and calcium and is a pathological hallmark of amyotrophic lateral sclerosis

2014

AbstractRedox control of proteins that form disulfide bonds upon oxidative challenge is an emerging topic in the physiological and pathophysiological regulation of protein function. We have investigated the role of the neuronal calcium sensor protein visinin-like protein 1 (VILIP-1) as a novel redox sensor in a cellular system. We have found oxidative stress to trigger dimerization of VILIP-1 within a cellular environment and identified thioredoxin reductase as responsible for facilitating the remonomerization of the dimeric protein. Dimerization is modulated by calcium and not dependent on the myristoylation of VILIP-1. Furthermore, we show by site-directed mutagenesis that dimerization is…

New Gold(I) Organometallic Compounds with Biological Activity in Cancer Cells

2014

N-Heterocyclic carbene gold(I) complexes bearing a fluorescent coumarin ligand were synthesized and characterized by various techniques. The compounds were examined for their antiproliferative effects in normal and tumor cells in vitro; they demonstrated moderate activity and a certain degree of selectivity. The compounds were also shown to efficiently inhibit the selenoenzyme thioredoxin reductase (TrxR), whereas they were poorly effective towards the glutathione reductase (GR) and glutathione peroxidase enzymes. Notably, {3-[(7-methoxy-2-oxo-2H-chromen-4-yl) methyl]-1-methylimidazol-2-ylidene}(tetra-O-acetyl-1-thio-beta-D-glucopyranosido) gold(I) (3) showed a pronounced inhibition of TrxR…

Inhibition of in vitro macrophage-induced low density lipoprotein oxidation by thyroid compounds

2003

Oxidized low density lipoproteins (LDL) are highly suspected of initiating the atherosclerosis process. Thyroid hormones and structural analogues have been reported to protect LDL from lipid peroxidation induced by Cu2+ or the free radical generator 2,2'-azobis-'2-amidinopropane' dihydrochloride in vitro. We have examined the effects of thyroid compounds on macrophage-induced LDL oxidation. Human monocyte-derived macrophages (differentiated U937 cells) were incubated for 24 h with LDL and different concentrations (0-20 microM) of 3,5,3'-triiodo-l -thyronine (T3), 3,5,3',5'-tetraiodo-L-thyronine (T4), 3,3',5'-tri-iodo-l -thyronine (rT3), the T3 acetic derivative (3,5,3'-tri-iodothyroacetic a…

Batch experiments for the determination of the Ti(IV,III) couple in 1 moldm-3 HCl, 2 moldm-3 NaCl medium at 25°C

2009

The determination of the Ti(IV, III) redox couple formal potential in 1 M HCl 2 M NaCl medium at 25°C through batch experiments involving the preparation of Ti(IV) and Ti(III) mixtures via the reaction of Ti(IV) with Zinc amalgam, has been carried out with emf measurements in order to verify the correctness of the previous value that the authors obtained by a coulometric-potentiometric investigation in the same conditions. The results from the two independent methods are in good agreement: 9 ± 1 mV the first and 9 ± 2 the average batch result.