scholarly journals Symposium on free radicals and diseases. The involvement of free radical formation in the post-ischemic neuronal damage.

1990 ◽  
Vol 79 (9) ◽  
pp. 1214-1218 ◽  
Author(s):  
Yasundo YAMASAKI ◽  
Kyuya KOGURE
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Neuronal Damage ◽  
Radical Formation ◽  
Free Radical Formation

Use of ESR to Investigate Formation of Free Radicals on Compounding Rubbers with Carbon Blacks

1978 ◽  
Vol 51 (1) ◽  
pp. 81-88 ◽  
Author(s):  
M. Jamroz˙ ◽  
K. Kozłowski ◽  
M. Sieniakowski ◽  
B. Jachym
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Radical Formation ◽  
Chemical Interactions ◽  
Carbon Blacks ◽  
Physicochemical State ◽  
Free Radical Formation ◽  
Open Question ◽  
Rubber Filler

Abstract The problem of rubber reinforcement is of great importance in rubber technology. Free radicals formed during mastication play an important role in the reinforcement of the rubber-filler system. The reinforcement of rubber systems is usually explained in terms of chemical interactions between rubber and filler; however, there are also opinions that the interactions are physical in nature. So far, the mechanism of reinforcement is an open question. Undoubtedly, reinforcement is influenced by free radicals formed during mastication and the physicochemical state of the surface of active fillers. The formation of free radicals during plasticization of rubbers has been already reported. Investigations by an ESR technique of free-radical formation during compounding of rubbers with various carbon blacks are described in the present paper.

scholarly journals Influence of Temperature on Free Radical Generation in Propolis-Containing Ointments

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Paweł Olczyk ◽  
Pawel Ramos ◽  
Katarzyna Komosinska-Vassev ◽  
Lukasz Mencner ◽  
Krystyna Olczyk ◽  
...  
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Heating Temperature ◽  
Radical Formation ◽  
Paramagnetic Resonance ◽  
Influence Of Temperature ◽  
Spin Lattice ◽  
Influence Of Temperature On ◽  
Free Radical Formation ◽  
C 50

Free radicals thermally generated in the ointments containing propolis were studied by electron paramagnetic resonance (EPR) spectroscopy. The influence of temperature on the free radical concentration in the propolis ointments was examined. Two ointment samples with different contents of propolis (5 and 7%, resp.) heated at temperatures of 30°C, 40°C, 50°C, and 60°C, for 30 min., were tested. Homogeneously broadened EPR lines and fast spin-lattice interactions characterized all the tested samples. Free radicals concentrations in the propolis samples ranged from 1018 to 1020 spin/g and were found to grow in both propolis-containing ointments along with the increasing heating temperature. Free radical concentrations in the ointments containing 5% and 7% of propolis, respectively, heated at temperatures of 30°C, 40°C, and 50°C were only slightly different. Thermal treatment at the temperature of 60°C resulted in a considerably higher free radical formation in the sample containing 7% of propolis when related to the sample with 5% of that compound. The EPR examination indicated that the propolis ointments should not be stored at temperatures of 40°C, 50°C, and 60°C. Low free radical formation at the lowest tested temperatures pointed out that both examined propolis ointments may be safely stored up to the temperature of 30°C.

scholarly journals Hydrogen Peroxide Effects on Natural-Sourced Polysacchrides: Free Radical Formation/Production, Degradation Process, and Reaction Mechanism—A Critical Synopsis

Foods ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 699
Author(s):  
Chigozie E. Ofoedu ◽  
Lijun You ◽  
Chijioke M. Osuji ◽  
Jude O. Iwouno ◽  
Ngozi O. Kabuo ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Free Radicals ◽  
Free Radical ◽  
Structural Characteristics ◽  
Radical Formation ◽  
Research Attention ◽  
Natural Sources ◽  
Polysaccharide Degradation ◽  
Free Radical Formation

Numerous reactive oxygen species (ROS) entities exist, and hydrogen peroxide (H2O2) is very key among them as it is well known to possess a stable but poor reactivity capable of generating free radicals. Considered among reactive atoms, molecules, and compounds with electron-rich sites, free radicals emerging from metabolic reactions during cellular respirations can induce oxidative stress and cause cellular structure damage, resulting in diverse life-threatening diseases when produced in excess. Therefore, an antioxidant is needed to curb the overproduction of free radicals especially in biological systems (in vivo and in vitro). Despite the inherent properties limiting its bioactivities, polysaccharides from natural sources increasingly gain research attention given their position as a functional ingredient. Improving the functionality and bioactivity of polysaccharides have been established through degradation of their molecular integrity. In this critical synopsis; we articulate the effects of H2O2 on the degradation of polysaccharides from natural sources. Specifically, the synopsis focused on free radical formation/production, polysaccharide degradation processes with H2O2, the effects of polysaccharide degradation on the structural characteristics; physicochemical properties; and bioactivities; in addition to the antioxidant capability. The degradation mechanisms involving polysaccharide’s antioxidative property; with some examples and their respective sources are briefly summarised.

scholarly journals Influence of Spray-Drying and Room Temperature Storage on the Anti- and Prooxidant Properties of Fermented Juçara Pulp

2020 ◽  
Vol 58 (1) ◽  
pp. 29-37
Author(s):  
Karla Bigetti Guergoletto ◽  
Kamila Landucci Bonifácio ◽  
Décio Sabbatini Barbosa ◽  
Daniel Farinha Valezi ◽  
Aroldo Salviato ◽  
...  
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Antioxidant Capacity ◽  
Spray Drying ◽  
Room Temperature ◽  
Gum Arabic ◽  
Radical Formation ◽  
Total Phenolic ◽  
Free Radical Formation ◽  
And Storage

Many fruits and vegetables contain compounds with antioxidant properties, but the processing and storage conditions of the food industry may damage these beneficial compounds and produce free radicals that are associated with oxidative stress. This study aims to evaluate in vitro the antioxidant capacity and prooxidant effects of juçara pulp fermented with Lactobacillus reuteri or Lactobacillus plantarum before and after spray-drying with maltodextrin, gum arabic or gelatin and storage at 25 °C for 90 days. The antioxidant capacity was assessed by measuring the ability to scavenge reactive oxygen species (ROS) in the neutrophil respiratory burst and free radical 2,2-diphenyl-1-picryl-hydrazyl (DPPH), and by determining the total phenolic content. The prooxidant effects were analyzed as free radical formation measured by electronic paramagnetic resonance (EPR). Fermentation by both bacteria increased the antioxidant activity, while the spray-drying process decreased the content of phenolic compounds (65-85 %) and the DPPH scavenging ability, depending on the carrier usage. All of the samples inhibited ROS in the neutrophil burst, and the juçara pulp fermented by L. reuteri and dried with gum arabic exhibited the best performance. Spray-drying did not influence the intensity or type of free radicals detected by EPR. However, storage at room temperature decreased the antioxidant capacity and increased free radical formation.

Blue ‘turn-on’ fluorescent probes for the direct detection of free radicals and nitric oxide in Pseudomonas aeruginosa biofilms

2016 ◽  
Vol 14 (7) ◽  
pp. 2272-2281 ◽  
Author(s):  
Mina Barzegar Amiri Olia ◽  
Athanasios Zavras ◽  
Carl H. Schiesser ◽  
Stefanie-Ann Alexander
Keyword(s):  
Nitric Oxide ◽  
Pseudomonas Aeruginosa ◽  
Free Radicals ◽  
Free Radical ◽  
Fluorescent Probes ◽  
Direct Detection ◽  
Radical Formation ◽  
Turn On ◽  
Blue Cell ◽  
Free Radical Formation

Novel blue cell-permeable ‘turn-on’ fluorescent probes have been developed to visualize and quantify nitric oxide and free radical formation and reaction within aPseudomonas aeruginosabiofilm.

Spectrochemistry of Polycarbohydrate Free Radicals Generated by Argon Plasmolysis: Effect of Tertiary Structure on Free Radical Formation

1994 ◽  
Vol 98 (44) ◽  
pp. 11301-11307 ◽  
Author(s):  
Masayuki Kuzuya ◽  
Kazue Morisaki ◽  
Junji Niwa ◽  
Yukinori Yamauchi ◽  
Kaijun Xu
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Tertiary Structure ◽  
Radical Formation ◽  
Free Radical Formation

scholarly journals A Rationale for Dopamine Agonists as Primary Therapy for Parkinson’s Disease

1992 ◽  
Vol 19 (S1) ◽  
pp. 108-112 ◽  
Author(s):  
C.W. Olanow
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Free Radical ◽  
Dopamine Agonists ◽  
Neuronal Damage ◽  
Radical Formation ◽  
Symptomatic Therapy ◽  
Primary Therapy ◽  
Clinical Control ◽  
Free Radical Formation

ABSTRACT:Levodopa is the most potent symptomatic treatment for Parkinson’s disease but adverse reactions are common and the initial response is not maintained. Further there is recent evidence that suggests that free radicals generated from the oxidative metabolism of dopamine may contribute to the pathogenesis of Parkinson’s disease. This raises the possibility that levodopa therapy by way of its conversion to dopamine may promote free radical formation and accelerate the rate of neuronal damage. Levodopa sparing strategies designed to minimize the cumulative levodopa dosage employed over the course of the disease seem a rational way to treat Parkinson patients in face of current information. Such a strategy would include the use of dopamine agonists as primary symptomatic therapy, the introduction of levodopa as an adjunct when dopamine agonists can no longer sufficiently provide satisfactory clinical control and the use of the lowest dose of levodopa that will provide satisfactory clinical control. In this way symptomatic control is not compromised on theoretical grounds, but the cumulative levodopa dose is minimized in an effort to reduce the likelihood of free radical formation with their potential adverse consequences on disease progression.

Interaction of cytokinins with lipid-associated oxy free radicals during senescence: a prospective mode of cytokinin action

1984 ◽  
Vol 62 (12) ◽  
pp. 2943-2949 ◽  
Author(s):  
Ya'acov Y. Leshem
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Xanthine Oxidase ◽  
Radical Scavenging ◽  
Free Radical Scavenger ◽  
Radical Formation ◽  
Radical Scavenger ◽  
Substrate Affinity ◽  
Xanthine Oxidase Inhibitors ◽  
Free Radical Formation

In senescence physiology, experimental data indicate causative relationships among cytokinin, lipoxygenation, anti-oxidation, and lipid-associated free radical scavenging. During both normal and induced senescence, there is a rise in lipoxygenase (LOX) which catalyzes the oxidation of polyunsaturated fatty acids containing the cis, cis-1,4-pentadiene configuration. These include linoleic and linolenic acids, which are of common occurrence in plants and inter alia may be situated in membranal phospholipids. Lipoxygenation causes the production of free radicals such as the superoxide, fatty acid, and peroxy species. Cytokinin (CK) lowers LOX and superoxide dismutase activities significantly in senescing foliage and is mimicked by the endogenous lipid antioxidant, α-tocopherol (vitamin E), in its chlorophyll-retaining and LOX-lowering effects. Further experimentation indicated that CK interaction with free radicals may occur in two ways, (i) CK may act as a direct free radical scavenger by virtue of the fact that the hydrogens of the α-carbon atom in the amine bond can be extracted, resulting in the formation of an amide: [Formula: see text][Formula: see text] (this mechanism may also, in part, explain polyamine effects), (ii) CK may serve as an incipient preventative of free radical formation by inhibiting oxidation of plant purine compounds, which at certain stages of breakdown release superoxide and hydroxyl free radicals. This effect is probably associated with a lowering of substrate affinity for xanthine oxidase. This assumption is further borne out by similar senescence-retarding effects of selective xanthine oxidase inhibitors such as allopurinol. These observations collectively indicate that prevention of free radical formation and (or) their direct scavenging should be included in the multifactorial antisencscence mode of action of cytokinin.

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