Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, ul. Goleva 13, Perm 614081, Russia.
Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, ul. Goleva 13, Perm 614081, Russia; Department of Chemistry and Biotechnology, Perm National Research Polytechnic University, Komsomolsky pr. 29, Perm 614990, Russia.
Microbiol Res. 2014 Apr;169(4):307-13. doi: 10.1016/j.micres.2013.06.013. Epub 2013 Jul 31.
Antioxidant activity of green and black tea and extracts of medicinal plants and their ability to modulate antibiotic susceptibility in Escherichia coli were studied. Among a number of extracts tested the maximal capacity to scavenge DPPH radicals and chelate iron in chemical tests was found in green and black tea, Arctostaphylos uva-ursi and Vaccinium vitis-idaea. These extracts contained high level of polyphenols and in aerobic conditions exhibited prooxidant features, producing H2O2 and inducing expression of the katG gene encoding catalase HPI in E. coli cells. A good correlation between the polyphenol content and the ability of extracts to protect bacteria against peroxide stress was observed (r = 0.88). Polyphenol-rich extracts and iron chelators demonstrated the highest modulating effect on the antibiotic susceptibility by changing the time period before lysis started and by influencing the colony-forming ability of bacteria. The direction of the modulating effect was dependent on nature of antibiotic applied: under treatment with ciprofloxacin and ampicillin the extracts predominantly provided protective effects, while under treatment with kanamycin a bactericidal action was enhanced. Mechanism of modulating action of extracts on bacterial antibiotic susceptibility probably involves antioxidant, preferentially iron-chelating, or prooxidant properties of polyphenols.
研究了绿茶、红茶和药用植物提取物的抗氧化活性及其对大肠杆菌抗生素敏感性的调节能力。在测试的许多提取物中，绿茶、熊果和越橘提取物在清除 DPPH 自由基和螯合铁的化学测试中具有最大的能力。这些提取物含有高水平的多酚，在有氧条件下表现出促氧化剂的特性，产生 H2O2 并诱导编码过氧化氢酶 HPI 的 katG 基因在大肠杆菌细胞中的表达。观察到多酚含量与提取物保护细菌免受过氧化物应激能力之间存在良好的相关性（r = 0.88）。多酚丰富的提取物和铁螯合剂通过改变开始裂解的时间和影响细菌的集落形成能力，对抗生素敏感性表现出最高的调节作用。调节作用的方向取决于应用的抗生素的性质：在用环丙沙星和氨苄西林处理时，提取物主要提供保护作用，而在用卡那霉素处理时，杀菌作用增强。提取物对细菌抗生素敏感性的调节作用机制可能涉及多酚的抗氧化、优先螯合铁或促氧化剂特性。
