Contribution of hydrogen peroxide to the cytotoxicity of green tea and red wines

Chai, Phing Chian; Long, Lee Hua; Halliwell, Barry

doi:10.1016/s0006-291x(03)00655-7

Cited by 119 publications

(69 citation statements)

References 24 publications

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“…Previous reports have suggested that EGCG at high concentrations produces ROS, especially H 2 O 2 , in cell cultures (Yang et al, 2000;Sakagami et al, 2001;Chai et al, 2003). The current findings confirmed this observation from two oral carcinoma cell lines, which demonstrated the formation of intracellular ROS when incubated with EGCG in a dosedependent manner (Fig.…”

Section: Discussionsupporting

confidence: 91%

Green Tea Polyphenol Causes Differential Oxidative Environments in Tumor versus Normal Epithelial Cells

Yamamoto¹,

Hsu²,

Lewis³

et al. 2003

J Pharmacol Exp Ther

137

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Green tea polyphenols (GTPPs) are considered beneficial to human health, especially as chemopreventive agents. Recently, cytotoxic reactive oxygen species (ROS) were identified in tumor and certain normal cell cultures incubated with high concentrations of the most abundant GTPP, (Ϫ)-epigallocatechin-3-gallate (EGCG). If EGCG also provokes the production of ROS in normal epithelial cells, it may preclude the topical use of EGCG at higher doses. The current study examined the oxidative status of normal epithelial, normal salivary gland, and oral carcinoma cells treated with EGCG, using ROS measurement and catalase and superoxide dismutase activity assays. The results demonstrated that high concentrations of EGCG induced oxidative stress only in tumor cells. In contrast, EGCG reduced ROS in normal cells to background levels. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and 5-bromodeoxyuridine incorporation data were also compared between the two oral carcinoma cell lines treated by EGCG, which suggest that a difference in the levels of endogenous catalase activity may play an important role in reducing oxidative stress provoked by EGCG in tumor cells. It is concluded that pathways activated by GTPPs or EGCG in normal epithelial versus tumor cells create different oxidative environments, favoring either normal cell survival or tumor cell destruction. This finding may lead to applications of naturally occurring polyphenols to enhance the effectiveness of chemo/radiation therapy to promote cancer cell death while protecting normal cells.

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Section: Discussionsupporting

confidence: 91%

Green Tea Polyphenol Causes Differential Oxidative Environments in Tumor versus Normal Epithelial Cells

Yamamoto¹,

Hsu²,

Lewis³

et al. 2003

J Pharmacol Exp Ther

137

View full text Add to dashboard Cite

show abstract

“…Caspase-3 activation appears to involve EGCG-induced ROS formation, whereas cytotoxicity and growth arrest do not. Endogenous catalase plays a role in the response of cells to EGCG; cells without adequate catalase are more sensitive to EGCG-induced H 2 O 2 formation, as shown in the current study and previous reports (Yang et al, 1998;Sakagami et al, 2001;Chai et al, 2003). However, H 2 O 2 alone cannot reproduce the EGCG effects in other cell lines or cell types.…”

Section: Discussionsupporting

confidence: 78%

“…This apoptotic pathway also involves activator protein-1 (AP-1) inactivation (Dong, 1997;Barthelman et al, 1998;Balasubramanian et al, 2002). Apoptosis induced by EGCG in certain in vitro cell models was reversed by exogenous catalase, suggesting that H 2 O 2 was the main cause of apoptotic pathway activation (Nakagawa et al, 2002;Chai et al, 2003). It was also noted that whereas at low concentrations EGCG (Ͻ10 M) functions as a ROS scavenger, at high concentrations it functions as a ROS producer and can cause DNA damage (100 M and above) (Saeki et al, 2002).…”

mentioning

confidence: 99%

Roles of Catalase and Hydrogen Peroxide in Green Tea Polyphenol-Induced Chemopreventive Effects

Yamamoto¹,

Lewis²,

Wataha³

et al. 2003

J Pharmacol Exp Ther

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The green tea polyphenol (Ϫ)-epigallocatechin-3-gallate (EGCG) possesses promising anticancer potential. Although in vivo studies unveiled the metabolic routes and pharmacokinetics of EGCG and showed no adverse effects, in vitro studies at high concentrations demonstrated oxidative stress. EGCG causes differential oxidative environments in tumor versus normal epithelial cells, but the roles that EGCG, hydrogen peroxide (H 2 O 2 ), and intracellular catalase play in the epithelial system are largely unknown. The current study employed enzyme activity assays, reactive oxygen species quantification, and immunoblotting to investigate whether EGCG-induced differential effects correlate with levels of key antioxidant enzymes and H 2 O 2 . It was found that normal human keratinocytes with high catalase activity are least susceptible to H 2 O 2 , whereas H 2 O 2 caused significant cytotoxicity in oral carcinoma cell lines. However, the EGCG-induced differential effects could not be duplicated by H 2 O 2 alone. The addition of exogenous catalase failed to completely prevent the EGCG-induced cytotoxicity and rescue the EGCG-induced growth arrest in the tumor cells. The antioxidant N-acetyl-L-cysteine rescued the tumor cells from H 2 O 2 -induced damage only, but not from EGCGinduced mitochondrial damage. Finally, alterations in catalase or superoxide dismutase activities were not observed upon EGCG exposure. In conclusion, although endogenous catalase may play a role in response to H 2 O 2 -induced cytotoxicity, the EGCG-induced cytotoxic effects on tumor cells mainly result from sources other than H 2 O 2 .

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“…In fact, the addition of the pro-oxidant activities of the alcohol and the alcohol-free stout combined gave a pro-oxidant plasma activity approximately equal to that of the alcoholic stout. This is consistent with the suggestion from Halliwell's laboratory that polyphenols can result in the production of peroxide in biological fluids (Long et al, 1999;Evans and Halliwell, 2001;Chai et al, 2003;Halliwell, 2003).…”

Section: Discussionsupporting

confidence: 92%

Alcohol: Friend or FOE? Alcoholic Beverage Hormesis for Cataract and Atherosclerosis is Related to Plasma Antioxidant Activity

Prickett

Lister

Collins

et al. 2004

Nonlinearity in Biology, Toxicology, Medicine

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Contribution of hydrogen peroxide to the cytotoxicity of green tea and red wines

Cited by 119 publications

References 24 publications

Green Tea Polyphenol Causes Differential Oxidative Environments in Tumor versus Normal Epithelial Cells

Green Tea Polyphenol Causes Differential Oxidative Environments in Tumor versus Normal Epithelial Cells

Roles of Catalase and Hydrogen Peroxide in Green Tea Polyphenol-Induced Chemopreventive Effects

Alcohol: Friend or FOE? Alcoholic Beverage Hormesis for Cataract and Atherosclerosis is Related to Plasma Antioxidant Activity

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