tempo and 6-hydroxy-2-5-7-8-tetramethylchroman-2-carboxylic-acid

A series of 4-alkanoyloxy-2,2,6,6-tetramethylpiperidinoxyl radicals was prepared, and their reactivity in water vis-à-vis antioxidant Trolox was compared. Spectral (electron paramagnetic resonance) and dynamic-light-scattering measurements suggested the formation of micelles for the more hydrophobic members of the series. The observed increase in reactivity for the micelle-forming radicals reflected the increased local concentration of the radical fragment on the micellar interface. Copyright © 2016 John Wiley & Sons, Ltd.

Topics: Antioxidants; Chromans; Cyclic N-Oxides; Electron Spin Resonance Spectroscopy; Free Radicals; Hydrophobic and Hydrophilic Interactions; Light; Micelles; Models, Molecular; Scattering, Radiation

Previous literature reports have demonstrated that nucleated trout erythrocytes in condition of oxidative stress are subjected to DNA and membrane damage, and inactivation of glutathione peroxidase. The present study was undertaken to investigate if mitochondrial membrane potential in stressed conditions was also influenced. Density-separated trout erythrocyte fractions, obtained using a discontinuous Percoll gradient, were submitted to stress conditions and the mitochondrial membrane potential was determined by means of cytofluorimetric analysis after incubation of each subfraction with JC-1, a mitochondrial specific fluorescent probe. The results clearly show that the mitochondrial membrane potential decreased significantly in all erythrocyte fractions, also if the oxidative effect on mitochondria is more severe with increased density (age) of the cell. Ebselen was very effective in preventing mitochondrial depolarization in young as well as in old erythrocytes.

Topics: Animals; Antioxidants; Azoles; Benzimidazoles; Carbocyanines; Cellular Senescence; Chromans; Cyclic N-Oxides; Erythrocytes; Flow Cytometry; Fluorescent Dyes; Free Radicals; In Vitro Techniques; Intracellular Membranes; Isoindoles; Membrane Potentials; Microscopy, Confocal; Mitochondria; Molecular Structure; Organoselenium Compounds; Oxidative Stress; Reactive Oxygen Species; Trout

Nitrone/nitroso spin traps are often used for detection of unstable hydroxyl radical giving stable nitroxide radicals with characteristic electron spin resonance (ESR) signals. This technique may be useful only when the nitroxide radicals are kept stable in the reaction system. The aim of the present study is to clarify whether the nitroxide radicals are kept stable in the presence of the hydroxyl radical scavengers. Effect of hydroxyl radical scavengers on the ESR signals of nitroxide radicals, 2,2,6,6-tetramethyl-piperidine- N-oxyl (TEMPO) and the spin adduct (DMPO-OH) of 5,5-dimethyl-1-pyrroline N-oxide (DMPO) and hydroxyl radical, was examined. Although the ESR signals of TEMPO and the DMPO-OH spin adduct were unchanged on treatment with ethanol and dimethyl sulfoxide, their intensities were effectively decreased on treatment with 6-hydroxy-2,5,7, 8-tetra-methylchroman-2-carboxylic acid (Trolox), cysteine, glutathione, 2-mercaptoethanol and metallothionein. Hence, the results of the detection of hydroxyl radical in the presence of phenolic and thiol antioxidants by the ESR technique using nitrone/nitroso spin traps may be unreliable.

Topics: Antioxidants; Chromans; Cyclic N-Oxides; Cysteine; Dimethyl Sulfoxide; Electron Spin Resonance Spectroscopy; Ethanol; Free Radical Scavengers; Free Radicals; Glutathione; Hydroxyl Radical; Mercaptoethanol; Metallothionein; Nitrogen Oxides; Phenols; Sulfhydryl Compounds

Sinusoidal endothelial cell injury plays a pivotal role in anoxia/reoxygenation liver damage. However, the mechanisms culminating in anoxia/reoxygenation endothelial cell injury remain unclear. Our aims were to determine whether anoxia/reoxygenation injury of sinusoidal endothelial cells causes mitochondrial dysfunction. In cultured rat liver sinusoidal endothelial cells, the mitochondrial membrane potential, cytosolic free calcium and cytosolic pH were quantitated by means of fluorescent probes and multiparameter digitized video microscopy. Cell viability was measured on the basis of lactate dehydrogenase release, and ATP was quantitated with a luciferin/luciferase assay. Mitochondrial membrane potential was stable during 90 min of aerobic perfusion. After 60 and 90 min of anoxia, mitochondrial membrane potential decreased gradually to 97% +/- 6% and 79% +/- 7% of the basal value, respectively. However, mitochondrial membrane potential decreased abruptly with reoxygenation after 60 min of anoxia to 45% +/- 12% of the basal value and did not recover over 30 min of aerobic perifusion. Loss of mitochondrial membrane potential could not be attributed to changes of cytosolic free calcium, cytosolic pH, nitric oxide generation or activity of poly(ADP-ribose) polymerase.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adenosine Triphosphate; Amino Acid Oxidoreductases; Animals; Antioxidants; Calcium; Cell Hypoxia; Cell Survival; Cells, Cultured; Chromans; Cyclic N-Oxides; Cyclosporine; Cytosol; Endothelium, Vascular; Glutathione; Hydrogen-Ion Concentration; Intracellular Membranes; Male; Membrane Potentials; Mitochondria, Liver; Nitric Oxide Synthase; Oxygen; Permeability; Poly(ADP-ribose) Polymerase Inhibitors; Rats; Rats, Sprague-Dawley; Trifluoperazine; Xanthine Oxidase