Mechanisms and Structural Specificity of Hydrogen Peroxide Formation during Oxidation of Catechins
Abstract:
Hydrogen peroxide (H2O2) formed in aqueous solutions of tea catechins such as epicatechin (EC), epicatechin gallate (ECg), epigallocatechin (EGC), and epigallocatechin gallate (EGCg) was measured by an HPLC method. The amount of H2O2 formed depended on their chemical structures, pH, temperature and incubation time. The gallyl moiety in the B-ring of the gallocatechins, namely EGC and EGCg, mainly contributed to the H2O2 formation. Superoxide dismutase inhibited oxidation of the gallocatechins and, consequently, the H2O2 formation. Cytotoxic effects were investigated by a colony formation assay with Chinese hamster V79 cells, and the effects of the gallocatechins were stronger than those of EC and ECg. The cytotoxic effects of the gallocatechins were inhibited completely by catalase and partially by superoxide dismutase. These results indicate that the gallocatechins were oxidized by superoxide, accompanied by the formation of H2O2, and their cytotoxic effects were ascribed to the H2O2 formation.read more
Citations
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Production of hydrogen peroxide by polyphenols and polyphenol-rich beverages under quasi-physiological conditions.
TL;DR: The features of the H2O2-generating property of green tea, black tea, and coffee were in good agreement with that of phenolic compounds, suggesting that polyphenols are responsible for the generation of H2 O2 in beverages.
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Kinetic study of catechin stability: effects of pH, concentration, and temperature.
TL;DR: An empirical model for catechin content was established as a function of pH and temperature and showed good correlation between green tea concentrated solutions and previous reports of catechine stability in powder systems, providing useful approaches for shelf life calculations and catechchin loss predictions at given temperature and pH conditions in green tea concentrates.
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Chemistry of secondary polyphenols produced during processing of tea and selected foods.
TL;DR: This review will discuss recent progress in the chemistry of secondary polyphenols produced during food processing, including the production mechanism of the secondary poly phenols in black tea, whisky, cinnamon, and persimmon fruits.
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Molecular Mechanisms Underlying the Flavonoid-Induced Inhibition of α-Synuclein Fibrillation
Xiaoyun Meng,Larissa A. Munishkina,Anthony L. Fink,Vladimir N. Uversky,Vladimir N. Uversky,Vladimir N. Uversky +5 more
TL;DR: The flavonoids inhibiting alpha-synuclein fibrillation and stabilizing the protein monomeric conformation can serve as a model for the development of therapeutic drugs in combating Parkinson's disease.
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Antioxidative and anti-hydrogen peroxide activities of various herbal teas
TL;DR: In this article, the anti-H 2 O 2 activity of herbal teas was examined, where various teas were added to a catechin-enriched green tea, and they were incubated at 25°C for one day.
References
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TL;DR: Interaction of tea catechins with lipid bilayer was investigated with liposome systems, which enabled us to separate liposomes from the external medium by centrifugation and found that epicatechin gallate had the highest affinity for lipid bilayers.