title: Medicinal plant extracts variously modulate susceptibility of Escherichia coli to different antibiotics.
abstract: 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.
authors.affiliation: Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, ul. Goleva 13, Perm 614081, Russia.
authors.forename: Zoya
authors.initials: Z
authors.lastname: Samoilova
authors.affiliation: Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, ul. Goleva 13, Perm 614081, Russia.
authors.forename: Galina
authors.initials: G
authors.lastname: Smirnova
authors.affiliation: Institute of Ecology and Genetics of Microorganisms, Russian Academy of Sciences, ul. Goleva 13, Perm 614081, Russia.
authors.forename: Nadezda
authors.initials: N
authors.lastname: Muzyka
authors.affiliation: 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. Electronic address: oktyabr@iegm.ru.
authors.forename: Oleg
authors.initials: O
authors.lastname: Oktyabrsky
mesh_terms: D000900:Anti-Bacterial Agents / Q000302:isolation & purification / Q000494:pharmacology*; D029792:Arctostaphylos / Q000737:chemistry*; D001713:Biphenyl Compounds / Q000378:metabolism; D002614:Chelating Agents / Q000302:isolation & purification / Q000494:pharmacology; D004336:Drug Antagonism; D004357:Drug Synergism; D004926:Escherichia coli / Q000187:drug effects*; D005609:Free Radicals / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D010851:Picrates / Q000378:metabolism; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*; D010946:Plants, Medicinal / Q000737:chemistry*; D059808:Polyphenols / Q000302:isolation & purification / Q000494:pharmacology; D029801:Vaccinium vitis-idaea / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D001713:Biphenyl Compounds; D002614:Chelating Agents; D005609:Free Radicals; D010851:Picrates; D010936:Plant Extracts; D059808:Polyphenols; C004931:1,1-diphenyl-2-picrylhydrazyl
keywords: Antibiotics; Bacteria; Medicinal plant extracts; Oxidative stress