Tea polyphenol epigallocatechin gallate inhibits Escherichia coli by increasing endogenous oxidative stress.
The antibacterial effects of tea polyphenol epigallocatechin gallate (EGCG), a common phytochemical with a number of potential health benefits, are well known. However, the mechanism of its bactericidal action remains unclear. Using E. coli as a model organism, it is argued here that H2O2 synthesis by EGCG is not attributed to its inhibitory effects. In contrast, the bactericidal action of EGCG was a result of increased intracellular reactive oxygen species and blunted adaptive oxidative stress response in E. coli due to the co-administration of antioxidant N-acetylcysteine, and not on account of exogenous catalase. Furthermore, we noted a synergistic bactericidal effect for EGCG when combined with paraquat. However, under anaerobic conditions, the inhibitory effect of EGCG was prevented. In conclusion, EGCG caused an increase in endogenous oxidative stress in E. coli, thereby inhibiting its growth, and hence the use of EGCG as a prooxidant is supported by this study.
Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha, Hunan 410128, China; National Research Center of Engineering Technology for Utilization of Functional Ingredients from Botanicals, Hunan Agricultural University, Changsha, Hunan 410128, China; Collaborative Innovation Centre of Utilisation of Functional Ingredients from Botanicals, Hunan Agricultural University, Changsha, Hunan 410128, China.
Li-Gui
LG
Xiong
Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha, Hunan 410128, China.
Yi-Jun
YJ
Chen
Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha, Hunan 410128, China.
Jie-Wen
JW
Tong
Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha, Hunan 410128, China; Collaborative Innovation Centre of Utilisation of Functional Ingredients from Botanicals, Hunan Agricultural University, Changsha, Hunan 410128, China.
Jian-An
JA
Huang
Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha, Hunan 410128, China; Collaborative Innovation Centre of Utilisation of Functional Ingredients from Botanicals, Hunan Agricultural University, Changsha, Hunan 410128, China.
Juan
J
Li
Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha, Hunan 410128, China. Electronic address: gongyushun@hunau.net.
Yu-Shun
YS
Gong
Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha, Hunan 410128, China; National Research Center of Engineering Technology for Utilization of Functional Ingredients from Botanicals, Hunan Agricultural University, Changsha, Hunan 410128, China; Collaborative Innovation Centre of Utilisation of Functional Ingredients from Botanicals, Hunan Agricultural University, Changsha, Hunan 410128, China. Electronic address: larkin-liu@163.com.
Zhong-Hua
ZH
Liu
D000111:Acetylcysteine / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D002374:Catalase / Q000378:metabolism; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects*; D006861:Hydrogen Peroxide / Q000737:chemistry; D018384:Oxidative Stress / Q000187:drug effects*; D059808:Polyphenols / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D013662:Tea / Q000737:chemistry*
D000975:Antioxidants; D059808:Polyphenols; D017382:Reactive Oxygen Species; D013662:Tea; D002392:Catechin; D006861:Hydrogen Peroxide; C045651:epigallocatechin gallate; D002374:Catalase; D000111:Acetylcysteine
Adaptive response; Antibacterial; Epigallocatechin gallate; Escherichia coli; Reactive oxygen species