Mechanisms of Antioxidant Action: The Antioxidant Activity of “Spin-Traps” in Rubber

1984 ◽  
Vol 57 (4) ◽  
pp. 779-791 ◽  
Author(s):  
L. P. Nethsinghe ◽  
G. Scott
Keyword(s):  
Antioxidant Activity ◽  
Mechanism Of Action ◽  
Nitroxyl Radicals ◽  
Antioxidant Action ◽  
Spin Traps ◽  
Phenolic Group ◽  
Stable Phenoxyl ◽  
High Level

Abstract A number of nitrones containing a partially hindered phenolic group are shown to be effective antidegradants for sulfur vulcanized rubbers. They exhibit a high level of antiozonant and antifatigue activity, but unlike commercial antiozonants they do not cause discoloration of light colored formulations. The new antidegradants are less effective than conventional additives as thermal antioxidants, but their performance as antifatigue agents and antioxidants is augmented by their use in combination with nonstaining antioxidants. The mechanism of action of the phenolic nitrones is believed to involve their oxidation to stable phenoxyl/nitroxyl radicals.

Mechanisms of Antioxidant Action: Aromatic Nitroxyl Radicals and Their Derived Hydroxylamines as Antifatigue Agents for Natural Rubber

1984 ◽  
Vol 57 (4) ◽  
pp. 735-743 ◽  
Author(s):  
H. S. Dweik ◽  
G. Scott
Keyword(s):  
Solvent Extraction ◽  
Natural Rubber ◽  
Mechanism Of Action ◽  
Nitroxyl Radical ◽  
Nitroxyl Radicals ◽  
Antioxidant Action ◽  
Sulfur Species

Abstract Diarylnitroxyl radicals and their reduction products, the diaryl hydroxylamines are effective anti-fatigue agents for rubber, confirming the previously proposed mechanism of action of the diaryamincs. The nitroxyls are reduced by sulfur species formed during the vulcanization reaction to a mixture of hydroxylamines and parent amines, and these species act as reservoirs for the nitroxyl radical during fatiguing. Removal of the reservoir of reduced species by solvent extraction removes the antifatigue activity.

scholarly journals Antioxidant activity of Spathodea campanulata (Bignoneaceae) extracts

2012 ◽  
Vol 14 (2) ◽  
pp. 287-292 ◽  
Author(s):  
S.C Heim ◽  
F.A Guarnier ◽  
D.T Ferreira ◽  
R Braz-Filho ◽  
R Cecchini ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Complex Formation ◽  
Mechanism Of Action ◽  
Iron Complex ◽  
Bark Extract ◽  
Flower Extract ◽  
Antioxidant Mechanism ◽  
Activity Loss ◽  
Ethanol Extracts ◽  
Antioxidant Mechanisms

Spathodea campanulata is used in traditional medicine in Africa as diuretic and anti-inflammatory. Although few studies have reported the mechanism of antioxidant action, this study evidenced the antioxidant activity of S. campanulata bark and flower extracts and their possible mechanism of action. Ethanol extracts of S. campanulata bark and flowers showed antioxidant activity on lipid peroxidation of liver microsome induced by Fe3+-ascorbic acid. Bark extract was 5 times more efficient than flower extract. The antioxidant activity of flower extract, previously complexed with increasing concentrations of Fe3+ (20 - 100 μM) which resulted in antioxidant activity loss, was shown to be related to iron complex formation. In contrast, the antioxidant activity of bark extract was not inhibited by the previous incubation with Fe3+, although complexation was demonstrated by spectral analysis of the solution. These results suggest an antioxidant mechanism other than Fe3+ complex formation. Therefore, the antioxidant mechanisms of S. campanulata flower and bark extracts are distinct from each other, reflecting the extract heterogeneous composition and the mechanism of action.

scholarly journals Again about carbonic anhydrase inhibitors: modern aspects of the use of ICA in ophthalmology

2021 ◽  
Vol 9 (2) ◽  
pp. 64-71
Author(s):  
P.A. Bezdetko
Keyword(s):  
Antioxidant Activity ◽  
Intraocular Pressure ◽  
Optic Nerve ◽  
Carbonic Anhydrase ◽  
Macular Edema ◽  
Mechanism Of Action ◽  
Corneal Endothelium ◽  
Complex Treatment ◽  
Efficacy And Safety ◽  
Carbonic Anhydrase Inhibitors

For more than 70 years, the inhibitors of carbonic anhydrase (ICA) have been used in the treatment of glaucoma. Since 1995, topical forms of ICA have appeared among antiglaucoma drugs — dorzolamide, and since 1999 — brinzolamide. The hypotensive efficacy and safety of topical ICA gave rise to the widespread use of these drugs in the treatment of various forms of glaucoma. The peculiarities of the mechanism of action made it possible to create on their basis effective fixed combinations, which allow reducing the intraocular pressure by up to 40 % in patients with glaucoma. The attractiveness of the drug has expanded due to the effect of ICA on various tissues of the organ of vision. Thus, ICAs effectively improve the hemodynamics of the eye and optic nerve. The antioxidant activity of the drug makes it possible to expand the indications for its use in patients with vascular patho-logy of the retina and optic nerve. The biomechanical characte-ristics of the drug allowed its effective and safe use in the complex treatment of macular edema of various etiologies. The adjuvant use of topical ICAs expands the possibilities of anti-VEGF therapy in the treatment of macular edema of various etiologies. Features of the action of ICA on the endothelial pump function of the cornea made it possible to formulate the rules for the use of topical ICA in patients with an insufficient function of the corneal endothelium.

scholarly journals Synthesis and Antioxidant of Some New Pyrazolo[1,5-a]pyrimidine, Pyrazolo[5,1-b]quinazoline and Imidazo[1,2-b]pyrazole Derivatives Incorporating Phenylsulfonyl Moiety

2021 ◽  
Vol 10 (3) ◽  
pp. 2414-2428
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Protective Effects ◽  
Oxidative Hemolysis ◽  
Elemental Analyses ◽  
Phenolic Group ◽  
High Antioxidant Activity ◽  
New Compounds

The synthesis and antioxidant of some new pyrazole analogs were described. It is achieved by the reaction of phenyl-4-(phenylsulfonyl)-1H-pyrazole-3,5-diamine (3) with different bifunctional reagents. The free radical-induced damage and the protective effects of the newly synthesized pyrazoles were studied. These new compounds inhibit the free radical-induced oxidative hemolysis of red blood cells effectively. It was found that these compounds effectively inhibit the free radical-induced oxidative hemolysis of red blood cells. Compound 5, which contain phenolic group, and 17, which bear sulfur, nitrogen atoms, and benzothiazole ring, respectively displayed high antioxidant activity. Analogs 15, 11, 10, and 9 were proved to exhibit antioxidative activity. Structures of new pyrazoles were confirmed by spectroscopic and elemental analyses and have been screened for their antioxidant activity.

scholarly journals Production and characteristics of fish protein hydrolysate from parrotfish (Chlorurus sordidus) head

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e8297 ◽  
Author(s):  
Asep A. Prihanto ◽  
Rahmi Nurdiani ◽  
Annas D. Bagus
Keyword(s):  
Antioxidant Activity ◽  
Protein Hydrolysate ◽  
Essential Amino Acids ◽  
Amino Acid Profile ◽  
Industrial Applications ◽  
Control Treatment ◽  
Degree Of Hydrolysis ◽  
Fish Protein ◽  
Fish Protein Hydrolysate ◽  
High Level

Background Fish byproducts are commonly recognized as low-value resources. In order to increase the value, fish byproducts need to be converted into new products with high functionality such as fish protein hydrolysate (FPH). In this study, FPH manufactured from parrotfish (Chlorurus sordidus) heads using different pH, time and sample ratio was investigated. Methods Hydrolysis reactions were conducted under different pHs (5, 7, and 9) and over different durations (12 and 24 h). Control treatment (without pH adjustment (pH 6.4)) and 0 h hydrolsisis duration were applied. Hydrolysates were characterized with respect to proximate composition, amino acid profile, and molecular weight distribution. The antioxidant activity of the hydrolysate was also observed. Results The pH and duration of hydrolysis significantly affected (p < 0.05) the characteristics of FPH. The highest yield of hydrolysate (49.04 ± 0.90%), with a degree of hydrolysis of 30.65 ± 1.82%, was obtained at pH 9 after 24 h incubation. In addition, the FPH had high antioxidant activity (58.20 ± 0.55%), with a high level of essential amino acids. Results suggested that FPH produced using endogenous enzymes represents a promising additive for food and industrial applications.

scholarly journals Comparison of the Total Polyphenol Content and Antioxidant Activity of Chocolate Obtained from Roasted and Unroasted Cocoa Beans from Different Regions of the World

Antioxidants ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 283 ◽  
Author(s):  
Bogumiła Urbańska ◽  
Jolanta Kowalska
Keyword(s):  
Antioxidant Activity ◽  
Total Content ◽  
Raw Material ◽  
Polyphenol Content ◽  
Cocoa Beans ◽  
Total Polyphenols ◽  
Total Polyphenol ◽  
Total Polyphenol Content ◽  
The World ◽  
High Level

The polyphenol content of cocoa beans and the products derived from them, depend on the regions in which they are grown and the processes to which they are subjected, especially temperature. The aim of the study was to compare the total content of polyphenols and antioxidant activity of chocolates obtained from roasted and unroasted cocoa beans. The chocolates produced from each of the six types of unroasted beans and each of the five types of roasted beans were investigated. The seeds came from Ghana, Venezuela, the Dominican Republic, Colombia and Ecuador. The highest total polyphenol content was determined in cocoa beans originating from Colombia and in the chocolates obtained from them. A higher content of total polyphenols was found in unroasted cocoa beans, which indicates the influence this process had on the studied size. The ability to scavenge free DPPH radicals was at a high level in both the beans and the chocolates produced from them, irrespective of the region where the raw material was grown. A positive correlation between the total polyphenol content and the ability to scavenge free radicals was found.

Natural Antioxidants in Hevea Latex

1948 ◽  
Vol 21 (3) ◽  
pp. 752-764 ◽  
Author(s):  
R. F. A. Altman
Keyword(s):  
Amino Acids ◽  
Antioxidant Activity ◽  
Water Layer ◽  
Natural Antioxidants ◽  
Antioxidant Action ◽  
Active Components ◽  
Naturally Occurring ◽  
Increasing Demand ◽  
Low Nitrogen ◽  
Soluble Fractions

Abstract An elaborate investigation on the identity and usefulness of the antioxidants naturally occurring in Hevea latex is of value because there is an increasing demand for special types of rubber with low nitrogen and ash contents, less water absorption, better electrical properties, and less odor than common crepe, and because these rubbers are generally unstable in comparison with the usual grades of rubber crepe and sheet. for the purpose of the investigation, fresh latex was separated into main-fractions, the most important of which have been called water-solubles and ether-solubles. These were further separated into various subfractions, which, one by one, have been tested for their antioxidant activity on raw rubber. In the following table only those fractions which show an outstanding antioxidant action are recorded. It is shown further that the amino acids are most remarkable in their antioxidant action : minute quantities exert a strong retarding action on the oxidation of raw rubber. Choline and cephaline are most probably the active components of the second water layer. The active ether-soluble fractions could not be identified due to the small quantities separated.

Sign in / Sign up

Export Citation Format

Share Document