Document Detail

Prooxidative effects of green tea polyphenol (-)-epigallocatechin-3-gallate on the HIT-T15 pancreatic beta cell line.
MedLine Citation:
PMID:  19757103     Owner:  NLM     Status:  MEDLINE    
Epigallocatechin-3-gallate (EGCG) is the main polyphenolic constituent in green tea and is believed to function as an antioxidant. However, increasing evidence indicates that EGCG produces reactive oxygen species (ROS) and subsequent cell death. In this study, we investigated the prooxidative effects of EGCG on the HIT-T15 pancreatic beta cell line. Dose-dependent cell viability was monitored with the cell counting kit-8 assay, while the induction of apoptosis was analyzed by a cell death ELISA kit and comet assay. Extracellular H(2)O(2) was determined using the Amplex Red Hydrogen Peroxide Assay Kit. Intracellular oxidative stress was measured by fluorometric analysis of 2',7'-dichlorofluorescin (DCFH) oxidation using DCFH diacetate (DA) as the probe. Treatment with EGCG (5-100 microM) decreased the viability of pancreatic beta cells, caused concomitant increases in apoptotic cell death, and increased the production of H(2)O(2) and ROS. Catalase, the iron-chelating agent diethylenetriaminepentaacetic acid, and the Fe(II)-specific chelator o-phenanthroline all suppressed the effects of EGCG, indicating the involvement of both H(2)O(2) and Fe(II) in the mechanism of action of EGCG. The antioxidant N-acetyl-cysteine and alpha-lipoic acid also suppressed the effects of EGCG. Furthermore, EGCG did not scavenge exogenous H(2)O(2), but rather, it synergistically increased H(2)O(2)-induced oxidative cell damage in pancreatic beta cells. Together, these findings suggest that in the HIT-T15 pancreatic beta cell line, EGCG mediated the generation of H(2)O(2), triggering Fe(II)-dependent formation of a highly toxic radical that in turn induced oxidative cell damage.
Kwang Sik Suh; Suk Chon; Seungjoon Oh; Sung Woon Kim; Jin-Woo Kim; Young Seol Kim; Jeong-Taek Woo
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-09-12
Journal Detail:
Title:  Cell biology and toxicology     Volume:  26     ISSN:  1573-6822     ISO Abbreviation:  Cell Biol. Toxicol.     Publication Date:  2010 Jun 
Date Detail:
Created Date:  2010-04-28     Completed Date:  2010-05-20     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8506639     Medline TA:  Cell Biol Toxicol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  189-99     Citation Subset:  IM    
Department of Endocrinology and Metabolism, Kyung Hee University School of Medicine, 1 Hoegi-dong, Dongdaemun-gu, Seoul 130-701, South Korea.
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MeSH Terms
Apoptosis / drug effects
Catechin / analogs & derivatives*,  toxicity
Cell Line
Cell Survival / drug effects
Comet Assay
Dose-Response Relationship, Drug
Flavonoids / toxicity
Hydrogen Peroxide / metabolism
Insulin-Secreting Cells / drug effects*,  metabolism
Oxidants / toxicity*
Oxidative Stress / drug effects
Phenols / toxicity
Reactive Oxygen Species / metabolism
Tea / chemistry
Reg. No./Substance:
0/Flavonoids; 0/Oxidants; 0/Phenols; 0/Reactive Oxygen Species; 0/Tea; 0/polyphenols; 154-23-4/Catechin; 7722-84-1/Hydrogen Peroxide; 989-51-5/epigallocatechin gallate

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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