Search results for "free radical"
showing 10 items of 263 documents
Does catalase play a role in Adriamycin induced cardiotoxicity?
1980
Summary Adriamycin causes an increase of lipid peroxidation in mouse cardiac homogenates that is dependent on the concentration of the antiblastic. The same phenomenon is not observed in the hearts of mice treated with an elevated dose of Adriamycin in which, conversely, an increase of the antioxidizing enzyme catalase was noticed. The significance of these findings is discussed with relationship to the hypothesis of an enhanced free radicals formation at the basis of Adriamycin induced cardiotoxicity.
γ-radiation-initiated polymerization of vinylidene fluoride in dense carbon dioxide
2002
The γ-ray-initiated batch polymerization of vinylidene fluoride (VF2) has been investigated in dense carbon dioxide under relatively mild operative conditions (T ≤ 40 °C and P < 25 MPa). When the initial VF2 molar concentration was increased from 3.4 to 6.4 mol/L, monomer conversion increased from 20 to 73%; a similar trend was observed for the number-average molecular weight and the molecular complexity of synthesized poly(vinylidene fluoride) (PVDF) as determined from rheological measurements. Under all adopted experimental conditions, a synthesized PVDF polymer was collected in the form of a white powder. Despite the inherent heterogeneous character of the polymerization process, a homog…
Contact probe voltammetry for in situ monitoring of the reactivity of phenolic tomato (Solanum lycopersicum L.) compounds with ROS
2015
The application of an in situ electrochemical contact probe methodology for monitoring reactivity of antioxidant polyphenolic compounds in tomato fruits is described. Upon electrochemical generation of reactive oxygen species (ROS), characteristic voltammetric responses were recorded for compounds resulting from the reaction of such species with tomato compounds. This suggests that new electrochemically oxidizable compounds are generated from the oxidation of highly reactive polyphenolic compounds with ROS. Therefore, an evaluation of the antioxidant capacity of such species could be made from voltammetric data for different tomato varieties.
Magnesium, Oxidative Stress, and Aging Muscle
2014
Abstract Magnesium (Mg) deficiency, aside from having a negative impact on the energy production pathways required by the mitochondria to generate ATP, also reduces the threshold antioxidant capacity of the aging organism and its resistance to free-radical damage. Mg acts as an antioxidant against free radical damage of the mitochondria. Chronic Mg deficiency results in excessive production of oxygen-derived free radicals and low-grade inflammation. Chronic inflammation and oxidative stress have been identified as pathogenic factors in several age-related conditions. Aging is often associated with Mg inadequacy, muscle loss, and sarcopenia. Although the importance of magnesium as a determin…
Synthesis of .beta.-ionone in an aldehyde/xanthine oxidase/.beta.-carotene system involving free radical formation
1994
The enzymic cooxidation of β-carotene (BC) by xanthine oxidase (XO) in aqueous solutions leads to β-ionone (BI) and derivatives: epoxy-β-ionone (EPBI), dihydroactinidiolide, β-cyclocitral, pseudoionone, etc. We demonstrate, in this article, that this is due to free radical (R . ) formation during the first hour of stirring and the use of aldehydes as substrate. The bleaching of BC does not occur when the common substrate of XO, xanthine, is used; this proves that the superoxide anion O 2 .- alone is not active on BC. BI formation in this case is not observed
[39] DNA damage induced by ultraviolet and visible light and its wavelength dependence
2000
Publisher Summary DNA damage induced by solar radiation in mammalian cells consists largely of two types of modification: pyrimidine dimers and oxidative modifications. Pyrimidine dimmers that can be subdivided into cyclobutane pyrimidine dimmers, (CPDs) and (6-4) photoproducts are the characteristic and most abundant modifications after direct excitation of DNA, although they can also be formed indirectly by energy transfer from other excited molecules such as carbonyl compounds. Oxidative DNA damage, which includes various pyrimidine and purine modifications, sites of base loss (AP sites), and strand breaks, is generated in only low yield after direct excitation of DNA (except at very sho…
Increased conformational rigidity of humic substances by oxidative biomimetic catalysis
2005
A synthetic water-soluble meso-tetra(2,6-dichloro-3-sulfonatophenyl)porphyrinate of iron(III) chloride, Fe(TDCPPS)Cl, was employed as a biomimetic catalyst in the oxidative coupling of terrestrial humic materials. High-performance size-exclusion chromatography (HPSEC), solid-state nuclear magnetic resonance (CPMAS-(13)C NMR), electron paramagnetic resonance (EPR), and diffuse reflectance infrared spectroscopy (DRIFT) were used to follow conformational and structural changes brought about in different humic materials by the oxidative coupling. Increase in apparent weight-average molecular weight (Mw(a)) occurred invariably for all humic substances with the oxidative polymerization catalyzed …
Gas phase behavior of radical cations of perfluoroalkyl-1,2,4-triazines: an experimental and theoretical study
2009
Electron ionization mass spectrometry and low-energy collision-induced decomposition reactions occurring in a tridimensional ion trap, together with density functional theory (DFT) calculations on neutrals, even- and odd-electron cations, have been used to study the gas-phase ion chemistry of a series of perfluoroalkyl-1,2,4-triazines. Loss of oxygen, due to thermal degradation occurring before ionization, likely involving the hydroxylamino group, has been observed. Compounds having a carbonyl group at position 6 of the triazine ring fragment in the source by elimination of NO followed by HF or CO. The decomposition pathways occurring due to CID experiments have shown interesting features d…
Chemical Composition and Free Radical Scavenging Activity of the Essential Oil of Achillea ligustica Growing Wild in Lipari (Aeolian Islands, Sicily)
2013
In the present study the chemical composition of the essential oils from aerial parts and flowers of Achillea ligustica All., collected in Lipari (Aeolian Islands) was evaluated by GC and GC-MS. ( Z)-Chrysanthenyl acetate was the most abundant component of both oils (29.6% in A1 and 27.8% in F1), followed by viridiflorol (16.8% in A1 and 21.6% in F1), bornyl acetate (8.7% in A1 and 11.6% in F1) and 1,8-cineole (7.4% in A1 and 9.3% in F1). A comparison was made of the composition of the different populations studied so far. Futhermore, the free radical scavenging activity of the oil was determined by DPPH and ABTS methods.
Impact of electron beam irradiation on fish gelatin film properties
2016
International audience; The objective of this work was to display the effect of electron beam accelerator doses on properties of plasticized fish gelatin film. Electron spin resonance indicates free radical formation during irradiation, which might induce intermolecular cross-linking. Tensile strength for gelatin film significantly increases after irradiation (improved by 30% for 60 kGy). The vapour permeability is weakly affected by irradiation. Surface tension and its polar component increase significantly and are in accordance with the increase of wettability. So, irradiation may change the orientation of polar groups of gelatin at the film surface and crosslink the hydrophobic amino aci…