Effects of Epigallocatechin Gallate on the Stability of Epicatechin in a Photolytic Process

Huang, Shih‐Yu; Hung, Yi-An; Yang, Meei-Ju; Chen, Iou-Zen; Yuann, Jeu-Ming P.; Liang, Ji-Yuan

doi:10.3390/molecules24040787

Cited by 25 publications

(24 citation statements)

References 38 publications

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“…The generated

can reduce NBT to form formazan, which can be detected at 560 nm. It has also been reported that catechin hydrate or epicatechin treated with BLI at 20 W/m 2 for 0–60 min generates

by the NBT reduction method [ 5 , 15 ]. The effects of AlCl 3 on the generation of

from the photolytic process of catechin were investigated in this study.…”

Section: Resultsmentioning

confidence: 99%

“…The depolymerization of BtPA via photooxidation in total chemical reactions by aluminum ion catalysis is represented in Equation (8) [ 46 , 49 ]. Subsequently, the carbocation ( Figure 10 H) can be reduced to generate catechin at m / z 289 ( Figure 10 A) [ 5 , 15 , 48 ].

…”

Section: Discussionmentioning

confidence: 99%

“…The effects due to BLI on the changes of catechin were studied by HPLC–MS analysis, as described by previous results [ 5 , 15 ]. The reactants were prepared as described in Section 4.3 .…”

Section: Methodsmentioning

confidence: 99%

“…In addition, a superoxide anion radical (

) can be produced upon the treatment of catechin with BLI [ 5 , 14 ]. The catechin or EC photolytic process can be inhibited by the addition of ascorbic acid or gallic acid during BLI, suggesting that these acids impede the electron-transfer mechanism in a photochemical reaction [ 5 , 15 ]. Catechin belonging to naturally occurring polyphenols is also unstable when treated with metal ions.…”

Section: Introductionmentioning

confidence: 99%

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Catechin Photolysis Suppression by Aluminum Chloride under Alkaline Conditions and Assessment with Liquid Chromatography–Mass Spectrometry

et al. 2020

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Tea is rich in catechins and aluminum. In this study, the process of catechin photolysis was applied as a model for examining the effects of aluminum chloride (AlCl3) on the structural changes of catechin and the alteration of aluminum complexes under blue light irradiation (BLI) at pH 8 using liquid chromatography and mass spectrometry techniques. Additionally, the effects of anions on catechin upon the addition of AlCl3 and treatment with BLI were also studied. In this study, when 1 mM catechin was treated with BLI, a superoxide anion radical (O2•−) was generated in an air-saturated aqueous solution, in addition to forming a dimeric catechin (proanthocyanidin) via a photon-induced redox reaction. The relative percentage of catechin was found to be 59.0 and 95.7 for catechin treated with BLI and catechin upon the addition of 1 mM AlCl3 treated with BLI, respectively. It suggested that catechin treated with BLI could be suppressed by AlCl3, while AlCl3 did not form a complex with catechin in the photolytic system. However, under the same conditions, it was also found that the addition of AlCl3 inhibited the photolytic formation of O2•−, and reduced the generation of proanthocyanidin, suggesting that the disconnection of proanthocyanidin was achieved by AlCl3 acting as a catalyst under treatment with BLI. The influence of 1 mM fluoride (F−) and 1 mM oxalate (C2O42−) ions on the photolysis of 1 mM catechin upon the addition of 1 mM AlCl3 and treatment with BLI was found to be insignificant, implying that, during the photolysis of catechin, the Al species were either neutral or negatively charged and the aluminum species did not form a complex with anions in the photolytic system. Therefore, aluminum, which is an amphoteric species, has an inherent potential to stabilize the photolysis of catechin in an alkaline conditions, while suppressing the O2•− and proanthocyanidin generation via aluminum ion catalysis in the catechin/Al system under treatment with BLI.

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“…The generated

can reduce NBT to form formazan, which can be detected at 560 nm. It has also been reported that catechin hydrate or epicatechin treated with BLI at 20 W/m 2 for 0–60 min generates

by the NBT reduction method [ 5 , 15 ]. The effects of AlCl 3 on the generation of

from the photolytic process of catechin were investigated in this study.…”

Section: Resultsmentioning

confidence: 99%

…”

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…In addition, a superoxide anion radical (

Section: Introductionmentioning

confidence: 99%

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Catechin Photolysis Suppression by Aluminum Chloride under Alkaline Conditions and Assessment with Liquid Chromatography–Mass Spectrometry

et al. 2020

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“…Shishido et al showed that when catechin is illuminated with ultraviolet A at 400 nm, its pro-oxidative mode is related to the formation of reactive oxygen species (ROS), as shown by an electron paramagnetic resonance (EPR) spin-trapping technique [23]. Under BLI and basic conditions, catechin forms a B-type proanthocyanidin, and O •− 2 is generated by photosensitized oxidation in a photolytic reaction and with the dimeric catechin at m/z 577 in a condensation reaction [4,24]. The proposed scheme for the photolysis of catechin is shown in Figure 2.…”

Section: Proposed Photoreaction Mechanism For Catechinmentioning

confidence: 99%

A Study of Catechin Photostability Using Photolytic Processing

et al. 2021

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Catechin exhibits numerous physiological characteristics. In this study, we determined the photosensitivity of catechin to various lights under alkaline conditions, and the mechanisms by which catechin generates free radical species and polymerizes via a photoreaction. In addition to this, the application of catechin photolysis was investigated. A solution of catechin is transparent, but turns yellowish under blue light illumination (BLI) in neutral or weak alkaline solutions. When catechin is subjected to BLI, a dimeric catechin (proanthocyanidin) and a superoxide anion radical (O2•−) are generated in a photolytic reaction. When ascorbic acid or gallic acid is added to catechin and the mixture is subjected to BLI at alkaline pH, fewer catechin dimers and less O2•− are produced, because both acids inhibit the photosensitive oxidation of catechin. When AlCl3 is added to catechin and the mixture is subjected to BLI at pH 8, a photolytic reaction is suppressed by AlCl3, and AlCl3 acts as a catalyst for the disconnection of proanthocyanidin during photolysis. Under alkaline conditions, catechin generates O2•− via photosensitive oxidation, which suppresses the growth of Acinetobacter baumannii (A. baumannii) by at least 4 logs, and deactivates its multi-drug-resistant strain. This study shows that catechin photolysis is a process of oxidation, and that it can be safely applied as a tool for environmental applications.

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Structure, stability and antioxidant activity of dialdehyde starch grafted with epicatechin, epicatechin gallate, epigallocatechin and epigallocatechin gallate

Kan

2022

J Sci Food Agric

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BACKGROUND Catechins, a member of the flavonoids, exist widely in teas, and have health benefits. However, catechins have poor stability, which greatly limits their application. In order to improve the stability of catechins, different catechins including (−)‐epicatechin (EC), (−)‐epicatechin gallate (ECG), (−)‐epigallocatechin (EGC) and (−)‐epigallocatechin gallate (EGCG) were conjugated onto dialdehyde starch by acid‐mediated coupling method. The structure, stability and antioxidant activity of dialdehyde starch–catechin conjugates were determined. RESULTS Thin‐layer chromatography and ultraviolet–visible spectroscopy, fluorescence, nuclear magnetic resonance and infrared spectra revealed that catechins were successfully conjugated onto dialdehyde starch, coupling between 6−H/8−H of catechins’ A ring and dialdehyde starch's aldehyde groups. The conjugates presented an amorphous structure and sheet‐like and/or blocky morphologies. As compared to dialdehyde starch, the conjugates showed enhanced thermal stability. Furthermore, the stability of catechins in pH 7.4 phosphate‐buffered saline was improved after conjugating onto dialdehyde starch. The conjugates exhibited significantly higher antioxidant activities than dialdehyde starch, decreasing in the following order: dialdehyde starch–ECG, dialdehyde starch–EGCG, dialdehyde starch–EC, dialdehyde starch–EGC and dialdehyde starch. CONCLUSION Dialdehyde starch–catechin conjugates have great potential as stable antioxidant agents. © 2022 Society of Chemical Industry.

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Effects of Epigallocatechin Gallate on the Stability of Epicatechin in a Photolytic Process

Cited by 25 publications

References 38 publications

Catechin Photolysis Suppression by Aluminum Chloride under Alkaline Conditions and Assessment with Liquid Chromatography–Mass Spectrometry

Catechin Photolysis Suppression by Aluminum Chloride under Alkaline Conditions and Assessment with Liquid Chromatography–Mass Spectrometry

A Study of Catechin Photostability Using Photolytic Processing

Structure, stability and antioxidant activity of dialdehyde starch grafted with epicatechin, epicatechin gallate, epigallocatechin and epigallocatechin gallate

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