It is well known that hydrogen peroxide (H2O2)-induced copper-catalyzed fragmentation of proteins follows a site-specific oxidative mechanism mediated by hydroxyl radical-like species (i.e. Cu(I)O, Cu(II)/*OH or Cu(III)) that ends in increased carbonyl formation and protein fragmentation. We have found that the nitrone spin trap DMPO (5,5-dimethyl-1-pyrroline N-oxide) prevented such processes b...

Plant plasma membranes are known to produce superoxide radicals, while the production of the hydroxyl radical, previously detected in complex plant tissues, is thought to occur in the cell wall. The mechanism of production of superoxide radicals by plant plasma membranes is, however, under dispute. It is shown, using electron paramagnetic resonance spectroscopy with a 5-diethoxyphosphoryl-5-met...

The objectives of this study were to investigate the effect of fermentation medium on the hydroxyl radical scavenging activity of exo-polysaccharides from Inonotus obliquus by response surface methodology. A two-level fractional factorial design was used to evaluate the effect of different components of medium. Corn flour, peptone, and KH2PO4 were important factors significantly affecting hydro...

1. Oxygen radicals in biological systems and the importance of iron Oxygen radicals can be either organic or inorganic. The organic radicals such as the peroxy (ROO') and alkoxy (RO') are those derived from complex molecules like the polyunsaturated fatty acids. The inorganic oxygen radicals are the superoxide radical (O,-*) and the hydroxyl radical (OH'). Formation of the highly reactive hydro...

The effects of four widely employed “antioxidants” on iron-mediated hydroxyl radical formation and lipid peroxidation were studied in aqueous model systems. Iron and copper served as catalysts for the reactions which oxidized ascorbic acid and alpha-tocopherol and reduced oxygen. Ferrous ion spontaneously reduced oxygen to 0; (superoxide anion radical) which led to .OH (hydroxyl radical) and Hz...

We evaluated the antioxidant properties of four main flavones from Scutellaria baicalensis: baicalein, wogonin and their glucuronides - baicalin and wogonoside. We used three in vitro assays: free radical scavenging with 2,2'-diphenylpicrylhydrazyl radical, transition metal ions reducing power by phosphomolybdenum assay and inhibition of the hydroxyl radical-induced peroxidation of linoleic aci...

A DFT study of U(VI) hydroxy complexes was performed with special attention paid to the [(UO2)3(OH)5(H2O)4-7]+ and [(UO2)4(OH)7(H2O)5-8]+ species. It was established that the ionicity of the U=O bond increased when moving from [(UO2)(H2O)5]2+, [(UO2)2(OH)(H2O)8]3+, [(UO2)2(OH)2(H2O)6]2+, [(UO2)3(OH)5(H2O)4-6]+ to [(UO2)4(OH)7(H2O)5-8]+ species. In both [(UO2)3(OH)5(H2O)4-6]+ and [(UO2)4(OH)7(H2...

The reaction between hydrogen peroxide and ferrous EDTA generates an oxidizing intermediate (I1) which is not the hydroxyl radical. It oxidizes ferrocytochrome c and also reacts with hydrogen peroxide (k5 = 3.2 X 10(3) M-1 S-1) to form a second oxidizing transient (I2). I1 is not scavenged by t-butyl alcohol whereas I2 is. I1 is found to be significantly less reactive than the hydroxyl radical ...

The objective of this investigation is to evaluate the hydroxyl radical (˙OH) generation using nanoporous activated carbon (NPAC), derived from rice husk, and dissolved oxygen in water. The in situ production of the ˙OH radical was confirmed through the DMPO spin trapping method in EPR spectroscopy and quantitative determination by a deoxyribose assay procedure. NPAC served as a heterogeneous c...

The photogeneration of hydroxyl radicals (OH(*)) in photosystem II (PSII) membranes was studied using EPR spin-trapping spectroscopy. Two kinetically distinguishable phases in the formation of the spin trap-hydroxyl (POBN-OH) adduct EPR signal were observed: the first phase (t(1/2) = 7.5 min) and the second phase (t(1/2) = 30 min). The generation of OH(*) was found to be suppressed in the absen...