Green tea polyphenols function as prooxidants to inhibit Pseudomonas aeruginosa and induce the expression of oxidative stress-related genes.
Green tea polyphenols (GTP) are widely believed to function as antioxidants and antimicrobial agents. Here we observed that GTP and epigallocatechin gallate, the most abundant catechin in GTP, could also function as prooxidants and produce hydrogen peroxide (H2O2) to inhibit the growth of Pseudomonas aeruginosa. pH value of the medium was the key factor that affected prooxidant versus antioxidant property of GTP. Under weakly acidic conditions (pH 5.5-6.5), GTP showed antioxidant activity by eliminating H2O2; whereas, under neutral and weakly alkaline conditions (pH 7.0-8.0), GTP showed prooxidant activity and inhibited the growth of P. aeruginosa. Furthermore, we studied the effects of GTP on gene expression profiles of a few oxidative stress-related genes by quantitative real-time PCR analysis. After 10 min to 1 h of exposure under weakly alkaline condition, GTP significantly up-regulated expression levels of katB, sodM, ohr, lexA, and recN gene. These findings highlight that the pH-dependent H2O2 production by GTP contributes to the antibacterial activity and can induce oxidative stress-related responses in P. aeruginosa.
Faculty of Basic Medicine, Zhejiang Medical College, Hangzhou, Zhejiang 310053, China.
Xiaoxiang
X
Liu
Jianrong
J
Li
Yanbo
Y
Wang
Tingting
T
Li
Jin
J
Zhao
Chaohua
C
Zhang
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology; D004262:DNA Restriction Enzymes / Q000235:genetics / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000032:analysis / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D018384:Oxidative Stress / Q000187:drug effects*; D010936:Plant Extracts / Q000032:analysis / Q000494:pharmacology*; D059808:Polyphenols / Q000032:analysis / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000254:growth & development; D017382:Reactive Oxygen Species / Q000032:analysis / Q000494:pharmacology*; D060888:Real-Time Polymerase Chain Reaction; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism; D013662:Tea / Q000737:chemistry*; D015854:Up-Regulation; D000099160:LexA Repressor Protein
D000900:Anti-Bacterial Agents; D000975:Antioxidants; D001426:Bacterial Proteins; D002392:Catechin; D004262:DNA Restriction Enzymes; D006861:Hydrogen Peroxide; D010936:Plant Extracts; D059808:Polyphenols; D017382:Reactive Oxygen Species; D012697:Serine Endopeptidases; D013662:Tea; D000099160:LexA Repressor Protein; C112257:organic hydroperoxide resistance protein, Xanthomonas campestris; C045651:epigallocatechin gallate; C047879:RecN protein, Bacteria