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.
- MeSH
- antibakteriální látky farmakologie MeSH
- antioxidancia farmakologie MeSH
- bakteriální proteiny genetika metabolismus MeSH
- čaj chemie MeSH
- katechin analogy a deriváty farmakologie MeSH
- koncentrace vodíkových iontů MeSH
- kvantitativní polymerázová řetězová reakce MeSH
- oxidační stres účinky léků MeSH
- peroxid vodíku analýza metabolismus MeSH
- polyfenoly analýza farmakologie MeSH
- Pseudomonas aeruginosa účinky léků růst a vývoj MeSH
- reaktivní formy kyslíku analýza farmakologie MeSH
- restrikční enzymy genetika metabolismus MeSH
- rostlinné extrakty analýza farmakologie MeSH
- serinové endopeptidasy genetika metabolismus MeSH
- upregulace MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
