Protective effect of methyl gallate from Toona sinensis (Meliaceae) against hydrogen peroxide-induced oxidative stress and DNA damage in MDCK cells

• Published in: Food and chemical toxicology Vol. 42; no. 5; pp. 843 - 850
• Main Authors: Hsieh, Tian-Jye, Liu, Tsan-Zon, Chia, Yi-Chen, Chern, Chi-Liang, Lu, Fung-Jou, Chuang, Man-chun, Mau, Shin-Yi, Chen, Shiang-Hsun, Syu, Yu-Hua, Chen, Ching-Hsein
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.05.2004; New York, NY Elsevier Science
• Subjects: analogs & derivatives; Animals; antagonists & inhibitors; antioxidant activity; Antioxidants; Antioxidants - pharmacology; Biological and medical sciences; cell culture; Cells, Cultured; chemistry; chemoprotection; Cytoprotection; DNA damage; DNA Damage - drug effects; Dogs; Dose-Response Relationship, Drug; drug effects; epicatechin; Gallic Acid; Gallic Acid - analogs & derivatives; Gallic Acid - chemistry; Gallic Acid - pharmacology; Glutathione; Glutathione - metabolism; Humans; Hydrogen peroxide; Hydrogen Peroxide - antagonists & inhibitors; Hydrogen Peroxide - pharmacology; kidney cells; Lipid peroxidation; Lipid Peroxidation - drug effects; Medical sciences; medicinal plants; Meliaceae; Meliaceae - chemistry; metabolism; Methyl gallate; Oxidative stress; Oxidative Stress - drug effects; pharmacology; plant extracts; protective effect; Reactive Oxygen Species; Reactive Oxygen Species - metabolism; roots; Toona; Toona sinensis; Toxicology; Methyl gallate; Oxidative stress; Hydrogen peroxide; Toona sinensis; DCF; DNA damage; Lipid peroxidation; DCFH-DA; ROS; MG; MDCK; CMF-DA; GSH; Glutathione; Prevention; DNA; Lipids; Peroxidation
• ISSN: 0278-6915; 1873-6351
• DOI: 10.1016/j.fct.2004.01.008

Methyl gallate (MG) has been shown to be an effective antioxidant in a variety of acellular experiments. Accordingly, this study was designed to assess the ability of MG, extracting from Toona sinensis to protect cultured Madin-Darby canine kidney (MDCK) cells against hydrogen peroxide (H 2O 2)-mediated oxidative stress. Trolox, a cell permeable and water-soluble vitamin E analogue, was included for comparison. First, when MDCK cells were pretreated with MG and trolox for 1 h, followed by exposing to H 2O 2 (0.8 mM) for an additional hour, we found that the intracellular peroxide productions, as reflected by dichlorofluorescein (DCF) fluorescence, were shown to be decreased in a concentration-dependent manner. Furthermore, using C 11-BODIPY 581/591 as a lipid peroxidation probe, we also found that MG, in a concentration of 100 μM, could alleviate lipid peroxidation of the cells exposed to a short-term H 2O 2 treatment. In addition, MG-treated cells could prevent intracellular glutathione (GSH) from being depleted following an exposure of H 2O 2 (8.0 mM) for a 3 h period. Next, we also examined the effect of MG on H 2O 2-mediated oxidative damage to DNA. Using 8-oxoguanine as an indicator for oxidative DNA damage, we demonstrated that the percentage of MDCK cells containing 8-oxoguanine was drastically increased by exposing to H 2O 2 (40 mM) for 3 h. However, 8-oxoguanine contents were shown to be significantly decreased in the presence of MG prior to H 2O 2 exposure. Comparatively, MG was shown to be a better protective agent against oxidative damage to DNA as compared to trolox. Taken together, our data suggest that MG is effective in preventing H 2O 2-induced oxidative stress and DNA damage in MDCK cells. The underlying mechanisms involved scavenging of intracellular reactive oxygen species (ROS), inhibition of lipid peroxidation and prevention of intracellular GSH depletion.