scholarly journals ANTIOXIDANT ACTIVITY OF MACROMOLECULAR COMPOUNDS OF HUMIC ETIOLOGY

2018 ◽  
pp. 239-250 ◽  
Author(s):  
Мария (Mariya) Владимировна (Vladimirovna) Зыкова (Zykova) ◽  
Людмила (Lyudmila) Анатольевна (Аnatol'evna) Логвинова (Logvinova) ◽  
Сергей (Sergej) Владимирович (Vladimirovich) Кривощеков (Krivoshchekov) ◽  
Олеся (Olesya) Александровна (Аleksandrovna) Воронова (Voronova) ◽  
Татьяна (Tat'yana) Викторовна (Viktorovna) Ласукова (Lasukova) ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Production Method ◽  
Proton Donor ◽  
Resonance Spectroscopy ◽  
Paramagnetic Resonance ◽  
Tomsk Region ◽  
Cathodic Voltammetry ◽  
Electron Paramagnetic ◽  
Spearman’S Correlation

Dependance of antioxidant activity of the humic macromolecular compounds from their etiology and production method was learned by means of physical-chemical analysis methods – colorimetry with diphenylpicrylhydrazyl (DPPH) as a stable radical, cathodic voltammetry, electron paramagnetic resonance spectroscopy. 18 native humic acids (HAs) were isolated by extraction from nine typical species of peats of the Tomsk region, that differ from each other by botanical composition, degree of decomposition and ash content. Two extragents were used: sodium hydroxide and sodium pyrophosphate. Although all 18 HAs samples exhibit antioxidant activity. At the same time there is a similar trend in the distribution of antioxidant activity, which is proved by Spearman's correlation analysis. А higher activity was noted for pyrophosphate HAs. Using methods of cathodic voltammetry and colorimetry with DPPH it was found that HAs show antioxidant activity by its mechanism, being a proton donor due to the presence of a large number of phenolic hydroxyls.EPR spectroscopy established that the HAs are traps of free radicals.

scholarly journals Teas: Direct Test on Quality and Antioxidant Activity using Electron Paramagnetic Resonance Spectroscopy

2002 ◽  
Vol 16 (3-4) ◽  
pp. 371-378 ◽  
Author(s):  
M. A. Morsy
Keyword(s):  
Antioxidant Activity ◽  
Electron Paramagnetic Resonance ◽  
Green Tea ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Oxidative Degradation ◽  
Paramagnetic Species ◽  
Resonance Spectroscopy ◽  
Stable Free Radical ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

The manufactured teas may conveniently be divided into three classes: Green teas, Oolongs (delicate black teas), and Black Teas. Several indirect methods are employed to measure the antioxidant activity of tea extracts that is basically takes place by monitoring the inhibition of oxidation of a suitable substrate using the extracts of antioxidant materials from the studies systems. This study is concerned with the results of electron paramagnetic resonance (EPR) spectroscopy that is utilized to investigate several categories of green and black teas: Twining Green Tea (TGT) of London, Rabea Green Tea (RGT) of Saudia, Chinese Green Tea (CGT) of China, English Breakfast Tea (EBT) of Ahmed Tea-London, and Rabea Black Tea (RBT) of Saudia. Three EPR signals from all the studied samples are observed. The assignment of these signals will discussed and correlated with the quality of leaves. Mainly, two paramagnetic species are considered to be responsible for the observed EPR signals; manganese(II)–protein system of the leaves and a stable free radical of aromatic origin. The study will provide facts on the dependency of radical signal on the oxidative degradation procedures of the studied samples. The intensity and feature of Mn(II)-EPR-signal is found to be related to the disintegration of tea leaves.

scholarly journals Tauroursodeoxycholic Acid (TUDCA)—Lipid Interactions and Antioxidant Properties of TUDCA Studied in Model of Photoreceptor Membranes

Membranes ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 327
Author(s):  
Michał J. Sabat ◽  
Anna M. Wiśniewska-Becker ◽  
Michał Markiewicz ◽  
Katarzyna M. Marzec ◽  
Jakub Dybas ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Plasma Membranes ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Protective Action ◽  
Antioxidant Properties ◽  
Model Membranes ◽  
Dynamics Simulation ◽  
Resonance Spectroscopy ◽  
Paramagnetic Resonance ◽  
Tauroursodeoxycholic Acid

Tauroursodeoxycholic acid (TUDCA), a hydrophilic bile acid containing taurine conjugated with the ursodeoxycholic acid (UDCA), has been known and used from ancient times as a therapeutic compound in traditional Chinese medicine. TUDCA has recently been gaining significant interest as a neuroprotective agent, also exploited in the visual disorders. Among several mechanisms of TUDCA’s protective action, its antioxidant activity and stabilizing effect on mitochondrial and plasma membranes are considered. In this work we investigated antioxidant activity of TUDCA and its impact on structural properties of model membranes of different composition using electron paramagnetic resonance spectroscopy and the spin labeling technique. Localization of TUDCA molecules in a pure POPC bilayer has been studied using a molecular dynamics simulation (MD). The obtained results indicate that TUDCA is not an efficient singlet oxygen (1O2 (1Δg)) quencher, and the determined rate constant of its interaction with 1O2 (1Δg) is only 1.9 × 105 M−1s−1. However, in lipid oxidation process induced by a Fenton reaction, TUDCA reveals substantial antioxidant activity significantly decreasing the rate of oxygen consumption in the system studied. In addition, TUDCA induces slight, but noticeable changes in the polarity and fluidity of the investigated model membranes. The results of performed MD simulation correspond very well with the experimental results.

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