Certain (−)-epigallocatechin-3-gallate (EGCG) auto-oxidation products (EAOPs) retain the cytotoxic activities of EGCG

Wei, Yaqing; Chen, Pingping; Ling, Tie-Jun; Wang, Yijun; Dong, Ruixia; Zhang, Chen; Zhang, Jinsong; Han, Manman; Wang, Dongxu; Wan, Xiaochun; Zhang, Jinsong

doi:10.1016/j.foodchem.2016.02.134

Cited by 77 publications

(76 citation statements)

References 37 publications

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“…Numerous reports have examined the instability of EGCG by means of HPLC and mass spectrometry [24], [35], [36]. The reported results are similar, namely, this compound degrades through oxidation pathways in a pH-dependent manner.…”

Section: Discussionmentioning

confidence: 78%

“…However, the details vary widely. For example, Bonfili et al [35] report that, at pH 8 and 37 °C, EGCG has a half-life of 75 min; whereas in the report of Wei et al [36], more than 75% of EGCG degrades after 1 h incubation at pH 8 and 37 °C. The chemical structures of oxidation products are also different from one another, probably originating from the experimental conditions and the methods of MS determination.…”

Section: Discussionmentioning

confidence: 99%

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Oxidized epigallocatechin gallate inhibited lysozyme fibrillation more strongly than the native form

Feng

Zeng

2017

Redox Biology

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Epigallocatechin gallate (EGCG), the most abundant flavanoid in green tea, is currently being evaluated in the clinic due to its benefits in the treatment of amyloid disorders. Its anti-amyloidogenic effect has been attributed to direct interaction of the intact molecule with misfolded polypeptides. In addition, antioxidant activity is also involved in the anti-amyloidogenic role. The detailed molecular mechanism is still unclear and requires further investigation. In the present study, the kinetics of EGCG oxidation and the anti-amyloidogenic effect of the resultant oxidation substances have been examined. The results indicate that EGCG degrades in a medium at pH 8.0 with a half-life less than 2 h. By utilizing lysozyme as an in vitro model, the oxidized EGCG demonstrates a more potent anti-amyloidogenic capacity than the intact molecule, as shown by ThT and ANS fluorescence, TEM determination, and hemolytic assay. The oxidized EGCG also has a stronger disruptive effect on preformed fibrils than the native form. Ascorbic acid eliminates the disruptive role of native EGCG on the fibrils, suggesting that oxidation is a prerequisite in fibril disruption. The results of this work demonstrate that oxidized EGCG plays a more important role than the intact molecule in anti-amyloidogenic activity. These insights into the action of EGCG may provide a novel route to understand the anti-amyloidogenic activity of natural polyphenols.

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Section: Discussionmentioning

confidence: 78%

Section: Discussionmentioning

confidence: 99%

Oxidized epigallocatechin gallate inhibited lysozyme fibrillation more strongly than the native form

Feng

Zeng

2017

Redox Biology

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“…Moreover, from the HPLC profiles and the MS determination, we could also deduce that under the selected experimental conditions, the epimerization and the hydrolysis of GCG represented the major reaction directions, while the auto‐oxidation was only a minor aspect. Based on the earlier‐mentioned analyses and the published results on EGCG, we present a tentative pathway (Scheme ) to explain the behavior of GCG in boiling water. We would point out that the stereochemistry of the oxidized product theasinensin is not specified on purpose in Scheme because it should be a mixture of theasinensin A/D generated from two molecules of EGCG and their isomers produced from two molecules of GCG or from one molecule of each of GCG and EGCG.…”

Section: Resultsmentioning

confidence: 99%

Stability and stabilization of (–)‐gallocatechin gallate under various experimental conditions and analyses of its epimerization, auto‐oxidation, and degradation by LC‐MS

Liang

et al. 2019

J Sci Food Agric

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BACKGROUND (–)‐Gallocatechin gallate (GCG) shows multi‐bioactivities. Its stability, however, has not been investigated systematically yet. Therefore, the objective of this study was to characterize the stability of GCG and to find ways to stabilize it in biological assays. Furthermore, the epimerization of the compound, its auto‐oxidation and degradation were also analyzed by liquid chromatography mass spectrometry (LC‐MS). RESULTS The stability of GCG was concentration‐dependent and was sensitive to pH, temperature, bivalent cations, and dissolved oxygen level. The results also showed that GCG was not stable in common buffers (50 mmol L−1, pH 7.4, 37 °C) or in cell culture medium DMEM/F12 under physiological conditions (pH 7.4, 37 °C). Our experiments indicated that nitrogen‐saturation and the addition of ascorbic acid (VC) could stabilize GCG in biological assays. In addition, LC‐MS determination indicated that GCG was able to be epimerized to its epimer (−)‐epigallocatechin gallate (EGCG). Meanwhile it was also able to be auto‐oxidized to theasinensin and compound P2 and degraded to gallocatechin and gallic acid in pure water at 100 °C. CONCLUSION The stability of GCG should be seriously considered in research on the bioactivity of it to avoid possible artifacts. Nitrogen‐saturation and use of VC are good ways to make GCG stable in biological assays. © 2019 Society of Chemical Industry

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“…EGCG is a predominant ingredient of catechins (Vuong et al 2010). There are broad application prospects for tea with high EGCG content due to its function in human health (Sur et al 2016;Wei et al 2016). However, EGCG can't be artificially synthesized at present, and it can only be extracted from tea.…”

Section: Discussionmentioning

confidence: 99%

A treasure reservoir of genetic resource of tea plant (Camellia sinensis) in Dayao Mountain

Jiang

Zhao

Zeng

et al. 2017

Genet Resour Crop Evol

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Components of 29 wild type tea single plants collected from Dayao Mountain, in Guangxi province, South China, were investigated. They included tea polyphenols, free amino acids, catechin, amino acid and alkaloid monomers etc. Genetic diversity and clustering analyses were conducted based on the main biochemical components. Meanwhile, genetic relationships among 6 wild type tea plants representing 3 tea populations of Daoyao Mountain with 15 tea varieties grown in Yunnan, Guangdong, Hunan, Fujian provinces were analyzed by random amplified polymorphic DNA. The results showed that wild type tea plants from Dayao Mountain were of rich genetic diversity. Furthermore, some tea germplasms with high quality, including high contents of amino acids, high epigallocatechin gallate, and high caffeine have been discovered. These wild type tea germplasms are of high values for further development values due to their geographical uniqueness.

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Certain (−)-epigallocatechin-3-gallate (EGCG) auto-oxidation products (EAOPs) retain the cytotoxic activities of EGCG

Cited by 77 publications

References 37 publications

Oxidized epigallocatechin gallate inhibited lysozyme fibrillation more strongly than the native form

Oxidized epigallocatechin gallate inhibited lysozyme fibrillation more strongly than the native form

Stability and stabilization of (–)‐gallocatechin gallate under various experimental conditions and analyses of its epimerization, auto‐oxidation, and degradation by LC‐MS

A treasure reservoir of genetic resource of tea plant (Camellia sinensis) in Dayao Mountain

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