Free Radical Motion in Super Critical Fluids Probed by EPR Spectroscopy

1998 ◽  
Vol 102 (3) ◽  
pp. 615-619 ◽  
Author(s):  
S. N. Batchelor
Keyword(s):  
Free Radical ◽  
Epr Spectroscopy

Investigation of Antioxidant Activity of Pomegranate Juices by Means of Electron Paramagnetic Resonance and UV-Vis Spectroscopy

2015 ◽  
Vol 98 (4) ◽  
pp. 866-870 ◽  
Author(s):  
Violetta Kozik ◽  
Krystyna Jarzembek ◽  
Agnieszka Jędrzejowska ◽  
Andrzej Bąk ◽  
Justyna Polak ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Free Radical ◽  
Epr Spectroscopy ◽  
Antioxidant Properties ◽  
Free Radical Scavenger ◽  
Pomegranate Juice ◽  
Radical Scavenger ◽  
Paramagnetic Resonance ◽  
Vis Spectroscopy ◽  
Electron Paramagnetic

Abstract Pomegranate fruit (Punica granatum L.) is a source of numerous phenolic compounds, and it contains flavonoids such as anthocyanins, anthocyanidins, cyanidins, catechins and other complexes of flavonoids, ellagitannins, and hydrolyzed tannins. Pomegranate juice shows antioxidant, antiproliferative, and anti-atherosclerotic properties. The antioxidant capacity (TEAC) of the pomegranate juices was measured using electron paramagnetic resonance (EPR) spectroscopy and 1,1-diphenyl-2-picrylhydrazyl (DPPH•) as a source of free radicals, and the total phenolic (TP) content was measured using UV-Vis spectroscopy. All the examined pomegranate juices exhibited relatively high antioxidant properties. The TEAC values determined by means of EPR spectroscopy using Trolox (TE) as a free radical scavenger were in the range of 463.12 to 1911.91 μmol TE/100 mL juice. The TP content measured by the Folin-Ciocalteu method, using gallic acid (GA) as a free radical scavenger, widely varied in the investigated pomegranate juice samples and ranged from 1673.62 to 5263.87 mg GA/1 L juice. The strongest antioxidant properties were observed with the fresh pomegranate juices obtained from the fruits originating from Israel, Lebanon, and Azerbaijan. Correlation analysis of numerical data obtained by means of EPR spectroscopy (TEAC) and UV-Vis spectroscopy (TP) gave correlation coefficient (r) = 0.90 and determination coefficient (r2) = 0.81 (P <0.05).

scholarly journals The Electronic Structure of the Cys-Tyr•Free Radical in Galactose Oxidase Determined by EPR Spectroscopy†

Biochemistry ◽  
2008 ◽  
Vol 47 (25) ◽  
pp. 6637-6649 ◽  
Author(s):  
Yuk-Ki Lee ◽  
Mei M. Whittaker ◽  
James W. Whittaker
Keyword(s):  
Electronic Structure ◽  
Free Radical ◽  
Epr Spectroscopy ◽  
Galactose Oxidase

scholarly journals Electron Paramagnetic Resonance Study of Thermally Treated Bismuth Subgallate

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Paweł Ramos ◽  
Barbara Pilawa
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Epr Spectroscopy ◽  
Electron Paramagnetic Resonance Study ◽  
Strong Interactions ◽  
Paramagnetic Resonance ◽  
Model Free ◽  
Different Temperatures ◽  
Bismuth Subgallate ◽  
Thermal Sterilization

Complex of bismuth, an anti-inflammatory drug, was studied by EPR spectroscopy. The aim of this study was to determine concentrations and properties of free radicals formed during thermal sterilization of bismuth subgallate according to pharmacopoeia norms to optimize its sterilization process. Different temperatures (160°C, 170°C, and 180°C) and times (120 minutes, 60 minutes, and 30 minutes) of sterilization were used. Interactions of bismuth subgallate with DPPH, the model free radical reference, were checked.g-Factors, amplitudes (A), integral intensities (I), and linewidths (ΔBpp) were obtained. Integral intensities were obtained by double integration of the first-derivative EPR lines. The influence of microwave power in the range of 2.2–70 mW on shape and parameters of the EPR spectra was examined. Thermal sterilization produced free radicals in bismuth subgallate in all tested cases. Strong interactions with free radicals were pointed out for all the analysed samples containing bismuth independent of sterilization conditions. Optimal conditions of thermal sterilization for bismuth subgallate with the lowest free radical formation are temperature 170°C and time of heating 60 minutes. Strong dipolar interactions exist in thermally sterilized bismuth subgallate. EPR spectroscopy is a useful method of examination of thermal sterilization conditions.

Free radical EPR spectroscopy analysis using blind source separation

2004 ◽  
Vol 166 (1) ◽  
pp. 82-91 ◽  
Author(s):  
J.Y. Ren ◽  
C.Q. Chang ◽  
P.C.W. Fung ◽  
J.G. Shen ◽  
F.H.Y. Chan
Keyword(s):  
Free Radical ◽  
Blind Source Separation ◽  
Epr Spectroscopy ◽  
Source Separation ◽  
Spectroscopy Analysis

Novel Bioadhesives for Restorative Dentistry

2008 ◽  
Vol 587-588 ◽  
pp. 682-686
Author(s):  
S.G. Pereira ◽  
J.P. Telo ◽  
R. Osorio ◽  
M. Toledano ◽  
Teresa G. Nunes
Keyword(s):  
Free Radical ◽  
Double Bond ◽  
Epr Spectroscopy ◽  
Stray Field ◽  
Restorative Dentistry ◽  
Radical Scavengers ◽  
Spatially Resolved ◽  
Radical Concentration ◽  
Free Radical Concentration ◽  
Double Bond Conversion

The objective of this study was to develop new adhesive formulations based on 2,2-bis[4-(2- methacryloxyprop-1-oxy) phenyl] propane (CH3-BisGMA) aiming to obtain high double bond conversion (DC) even in the presence of radical scavengers and monomers with acidic groups. NMR, EPR spectroscopy and spatially-resolved 1H Stray-Field MRI observations enabled to study the influence of the composition in DC, free radical concentration, reactivity of the monomers and volumetric contraction.

scholarly journals Porphyrin containing isoindoline nitroxides as potential fluorescence sensors of free radicals

2011 ◽  
Vol 15 (04) ◽  
pp. 230-239 ◽  
Author(s):  
Guo-Ping Yan ◽  
Kathryn E. Fairfull-Smith ◽  
Craig D. Smith ◽  
Graeme R. Hanson ◽  
Steven E. Bottle
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Epr Spectroscopy ◽  
Continuous Wave ◽  
Dipolar Coupling ◽  
Spin Coupling ◽  
Intersystem Crossing ◽  
Fluid Solution ◽  
Free Base ◽  
Fluorescence Sensors

A series of new spin-labeled porphyrin containing isoindoline nitroxide moieties were synthesized and characterized as potential free radical fluorescence sensors. Fluorescence-suppression was observed in the free-base monoradical porphyrins, whilst the free-base biradical porphyrins exhibited highly suppressed fluorescence about three times greater than the monoradical porphyrins. The observed fluorescence-suppression was attributed to enhanced intersystem crossing resulting from electronexchange between the doublet nitroxide and the excited porphyrin fluorophore. Notably, fluorescencesuppression was not as strong in the related metalated porphyrins, possibly due to insufficient spin coupling between the nitroxide and the porphyrin. Continuous wave EPR spectroscopy of the diradical porphyrins in fluid solution suggests that the nitroxyl-nitroxyl interspin distance is long enough and tumbling is fast enough not to detect dipolar coupling.

Evaluation of oxidative stability of vegetable oils enriched with herb extracts by EPR spectroscopy

2015 ◽  
Vol 69 (7) ◽  
Author(s):  
Mariola Kozłowska ◽  
Katarzyna Zawada
Keyword(s):  
Free Radical ◽  
Lipid Oxidation ◽  
Vegetable Oils ◽  
Epr Spectroscopy ◽  
Unsaturated Fatty Acids ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Radical Scavenging ◽  
Spin Trapping ◽  
Resonance Spectroscopy ◽  
Herb Extracts

AbstractVegetable oils are important constituents of a healthy diet. Still, unsaturated fatty acids present in vegetable oils are susceptible to oxidation, which leads to undesirable changes in sensory, chemical and nutritional properties of oils. To prevent this problem, antioxidants are applied with herbs and spices being one of the most important sources of natural antioxidants. Electron paramagnetic resonance spectroscopy (EPR) can be used to detect free radicals, which are the short-lived intermediates of lipid oxidation, and to monitor changes in oxidation susceptibility. In this study, the ESR spin trapping technique was used as a potential method for the evaluation of the resistance to free radical formation in rapeseed and sunflower oils enriched with herb extracts. The antioxidant effect of herb extracts on vegetable oils was also investigated by measuring their ability to scavenge DPPH free radical using EPR spectroscopy. The herb extracts generally improved the radical scavenging properties of sunflower and rapeseed oils but their influence on the onset of rapid lipid oxidation as measured by spin-trapping EPR depended on the type of oil and on the extract concentration.

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