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Author: Hahn, Veronika × Subject: Antimicrobial activity ×

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Now showing 1 - 2 of 2
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    Laccase‐Catalyzed Derivatization of Aminoglycoside Antibiotics and Glucosamine
    (Basel : MDPI, 2022) Mikolasch, Annett; Lindequist, Ulrike; Witt, Sabine; Hahn, Veronika
    The increasing demand for new and effective antibiotics requires intelligent strategies to obtain a wide range of potential candidates. Laccase‐catalyzed reactions have been successfully applied to synthesize new β‐lactam antibiotics and other antibiotics. In this work, laccases from three different origins were used to produce new aminoglycoside antibiotics. Kanamycin, tobramycin and gentamicin were coupled with the laccase substrate 2,5‐dihydroxy‐N‐(2‐hydroxyethyl)‐benzamide. The products were isolated, structurally characterized and tested in vitro for antibacterial activity against various strains of Staphylococci, including multidrug‐resistant strains. The cytotoxicity of these products was tested using FL cells. The coupling products showed comparable and, in some cases, better antibacterial activity than the parent antibiotics in the agar diffusion assay, and they were not cytotoxic. The products protected mice against infection with Staphylococcus aureus, which was lethal to the control animals. The results underline the great potential of laccases in obtaining new biologically active compounds, in this case new antibiotic candidates from the class of aminoglycosides.
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    Plasma-activation of larger liquid volumes by an inductively-limited discharge for antimicrobial purposes
    (Basel : MDPI, 2019) Schmidt, Michael; Hahn, Veronika; Altrock, Beke; Gerling, Torsten; Gerber, Ioana Cristina; Weltmann, Klaus-Dieter; von Woedtke, Thomas
    A new configuration of a discharge chamber and power source for the treatment of up to 1 L of liquid is presented. A leakage transformer, energizing two metal electrodes positioned above the liquid, limits the discharge current inductively by utilizing the weak magnetic coupling between the primary and secondary coils. No additional means to avoid arcing (electric short-circuiting), e.g., dielectric barriers or resistors, are needed. By using this technique, exceeding the breakdown voltage leads to the formation of transient spark discharges, producing non-thermal plasma (NTP). These discharges effected significant changes in the properties of the treated liquids (distilled water, physiological saline solution, and tap water). Considerable concentrations of nitrite and nitrate were detected after the plasma treatment. Furthermore, all tested liquids gained strong antibacterial efficacy which was shown by inactivating suspended Escherichia coli and Staphylococcus aureus. Plasma-treated tap water had the strongest effect, which is shown for the first time. Additionally, the pH-value of tap water did not decrease during the plasma treatment, and its conductivity increased less than for the other tested liquids. © 2019 by the authors.