Chemiluminescence analysis of the prooxidant and antioxidant effects of epigallocatechin-3-gallate.
The aim of this study was to investigate the mechanism of antioxidant and prooxidant effects of epigallocatechin-3-gallate (EGCG) using chemiluminescence analysis. Results showed that EGCG scavenged superoxide radical and H2O22 in a dose dependent manner. EGCG scavenged 50% of superoxide radical at 0.31 mM and scavenged 50% of H2O22 at 0.09 mM, demonstrating that EGCG has a stronger reactive oxygen species (ROS) scavenging activity than ascorbic acid. Effects of EGCG on free radical-induced DNA oxidative damage were investigated. EGCG had protective effect on DNA at low concentrations (2-30 mM), but it enhanced the DNA oxidative damage at higher concentrations (>60 mM), exhibiting a prooxidant effect on DNA. EGCG showed a greater reducing power on iron ions, reducing Fe3+ to Fe2+, which accelerates the generation of hydroxyl radical from the Fenton reaction. At low concentrations, ROS scavenging activity of EGCG might predominate over its reducing power and lead to its protective effect on DNA. However, relatively higher reducing power of EGCG at higher concentrations may gradually predominate over its ROS scavenging activity and result in the prooxidant effect of EGCG on DNA.
Tian
Bing
B
Institute of Nuclear-Agricultural Sciences, Zhejiang University, 268 Kaixuan Road, Hangzhou, Zhejiang, China 310029.
Sun
Zongtao
Z
Xu
Zhenjian
Z
Hua
Yuejin
Y
D000975:Antioxidants / Q000032:analysis / Q000737:chemistry* / Q000494:pharmacology; D001205:Ascorbic Acid / Q000032:analysis / Q000737:chemistry / Q000494:pharmacology; D002392:Catechin / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry / Q000494:pharmacology; D004249:DNA Damage / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D058870:Food, Organic; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D007501:Iron; D049449:Luminescence; D010084:Oxidation-Reduction / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000737:chemistry*; D013481:Superoxides / Q000737:chemistry; D013662:Tea / Q000737:chemistry*
D000975:Antioxidants; C045076:Fenton's reagent; D017382:Reactive Oxygen Species; D013662:Tea; D013481:Superoxides; D002392:Catechin; D006861:Hydrogen Peroxide; C045651:epigallocatechin gallate; D007501:Iron; D001205:Ascorbic Acid