Chain-Breaking Antioxidant Activity and Cyclic Voltammetry Characterization of Polyphenols in a Range of Green, Oolong, and Black Teas

2003 ◽  
Vol 51 (19) ◽  
pp. 5798-5802 ◽  
Author(s):  
Vitaly Roginsky ◽  
Tatyana Barsukova ◽  
Chyong F. Hsu ◽  
Paul A. Kilmartin
Keyword(s):  
Antioxidant Activity ◽  
Cyclic Voltammetry ◽  
Chain Breaking

scholarly journals Methods to Determine Chain-Breaking Antioxidant Activity of Nanomaterials beyond DPPH•. A Review

Antioxidants ◽  
2021 ◽  
Vol 10 (10) ◽  
pp. 1551
Author(s):  
Andrea Baschieri ◽  
Riccardo Amorati
Keyword(s):  
Antioxidant Activity ◽  
Chemical Methods ◽  
Testing Conditions ◽  
Radical Trapping ◽  
Chain Breaking ◽  
Stable Radicals ◽  
Further Development ◽  
Selection Of ◽  
Made In

This review highlights the progress made in recent years in understanding the mechanism of action of nanomaterials with antioxidant activity and in the chemical methods used to evaluate their activity. Nanomaterials represent one of the most recent frontiers in the research for improved antioxidants, but further development is hampered by a poor characterization of the ‘‘antioxidant activity’’ property and by using oversimplified chemical methods. Inhibited autoxidation experiments provide valuable information about the interaction with the most important radicals involved in the lipid oxidation, namely alkylperoxyl and hydroperoxyl radicals, and demonstrate unambiguously the ability to stop the oxidation of organic materials. It is proposed that autoxidation methods should always complement (and possibly replace) the use of assays based on the quenching of stable radicals (such as DPPH• and ABTS•+). The mechanisms leading to the inhibition of the autoxidation (sacrificial and catalytic radical trapping antioxidant activity) are described in the context of nanoantioxidants. Guidelines for the selection of the appropriate testing conditions and of meaningful kinetic analysis are also given.

scholarly journals Analysis of Antioxidant and Antiallergic Active Components Extracted From the Edible Insect Oxya yezoensis

2021 ◽  
Vol 16 (5) ◽  
pp. 1934578X2110233
Author(s):  
Masahiro Saiki ◽  
Naomichi Takemoto ◽  
Maki Nagata ◽  
Masako Matsumoto ◽  
Yhiya Amen ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Phenolic Compounds ◽  
Unsaturated Fatty Acids ◽  
Soluble Fraction ◽  
Total Phenolic ◽  
Key Factors ◽  
Active Components ◽  
Food And Agriculture ◽  
Food And Agriculture Organization

In recent years, entomophagy has attracted increased attention, as it was recommended as a potential source of food by the Food and Agriculture Organization of the United Nations. In Japan, Oxya yezoensisis one of the most widely eaten insect species, but studies of its functionality as a food are limited. In this study, we reported the optimal characterization of the total phenolic compounds in methanolic extract (OME) and different fractions of OME. Additionally, the antioxidant and antiallergic activities of the OME fractions were evaluated. The results showed that the ethyl acetate-soluble fraction of OME has potential antioxidant activity, whereas the n-hexane-soluble fraction showed the strongest inhibition of β-hexosaminidase, which is one of the key factors in allergic reactions. It was concluded that phenolic compounds might contribute to the antioxidant activity while unsaturated fatty acids contribute to the antiallergy activity.

Synthesis and characterization of novel functionalized perarylated polysiloxane for proton exchange membrane fuel cells

MRS Advances ◽  
2019 ◽  
Vol 4 (64) ◽  
pp. 3579-3585
Author(s):  
Guillermo M. González Guerra ◽  
Alejandro Alatorre-Ordaz ◽  
Gerardo González Garcia ◽  
Jesus S. Jaime-Ferrer
Keyword(s):  
Cyclic Voltammetry ◽  
Fuel Cells ◽  
Proton Exchange Membrane ◽  
Area Under The Curve ◽  
Chlorosulfonic Acid ◽  
Proton Exchange ◽  
Synthesis And Characterization ◽  
A Value ◽  
Exchange Membrane

ABSTRACTThis work presents the synthesis and characterization of a pearylated polysiloxane material (PAP) from a polycondensation reaction, followed by functionalization with HClSO3 by an electrophilic substitution reaction. According to the characterization techniques applied, a sulfonated pearylated polysiloxane was also obtained, (SPAP). The purpose of this sulfonated material is to obtain an ionomer able to be applied in hydrogen fuel cells of the proton exchange membrane kind (PEMFC). The reaction to produce the polysiloxane precursor was carried out with the commercial reagents: PhSiCl3, Ph2SiCl2 and Ph3SiCl in anhydrous THF at 75 °C and the SPAP material was obtained by sulfonation of the precursor with chlorosulfonic acid. PAP and SPAP were characterized by 1H, NMR for liquids, 29Si NMR for solids, IR-ATR, SEM, and cyclic voltammetry. The NMR 29Si spectra show that PAP and PAPS contain crosslinking regions due to PhSiCl3, growing chain zones due to Ph2SiCl2 and polymer termination zones due to Ph3SiCl, obtaining a mixture of siloxanes. The analysis by cyclic voltammetry indicates that by integrating the area under the curve of the adsorption peaks of H2, a value of 0.062 mC/cm2 is obtained, a value close to the commercial ionomer of Nafion®.

scholarly journals Characterization of phenolic compounds and antioxidant properties of Glycyrrhiza glabra L. rhizomes and roots

RSC Advances ◽  
2015 ◽  
Vol 5 (34) ◽  
pp. 26991-26997 ◽  
Author(s):  
Natália Martins ◽  
Lillian Barros ◽  
Montserrat Dueñas ◽  
Celestino Santos-Buelga ◽  
Isabel C. F. R. Ferreira
Keyword(s):  
Antioxidant Activity ◽  
Phenolic Compounds ◽  
Antioxidant Properties ◽  
Glycyrrhiza Glabra ◽  
Phenolic Composition ◽  
Glycyrrhiza Glabra L

The present work aims to characterize and quantify the phenolic composition and to evaluate the antioxidant activity of Glycyrrhiza glabra L. (commonly known as licorice) rhizomes and roots.

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