Results of our experiments indicate that ionic strength of the incubation medium influence the selectivity, the medium temperature and the assay conditions impact the kinetics of efflux. The lower accumulated amount and the weaker fluorescence of Et registered in slightly acidic medium indicate that ΔΨ plays a role in the accumulation of this indicator cation. The bound amount of Et to the de-energized or permeabilized cells considerably varies depending on the conditions and methods of de-energization or permeabilization of cells. Tris/EDTA permeabilization of the cells does not inhibit the efflux.
We synthesized a set of 13 new and earlier described styrylpyridinium compounds (N‐alkyl styrylpyridinium salts with bromide or tosylate anions) in order to evaluate antifungal activity against C. albicans cells, to assay the possible synergism with fluconazole, and to estimate cytotoxicity to mammalian cells. All compounds were synthesized according to a well‐known two‐step procedure involving alkylation of γ‐picoline with appropriate alkyl bromide and further condensation with substituted benzaldehyde. Compounds with long N‐alkyl chains (C18H37–C20H41) had no antifungal activity against the cells of all tested C. albicans strains. Other styrylpyridinium compounds were able to inhibit yeast growth at the concentrations of 0.06–16 μg/ml. At fungicidal concentrations, the compound with the CN‐ group was least toxic to mammalian cells, showed the most effective synergism with fluconazole, and only slightly inhibited the respiration of C. albicans. The compound with the 4′‐diethylamino group exhibited the strongest fungicidal properties and effectively blocked the respiration of C. albicans cells. However, toxicity to mammalian cells was also high. Summarizing, the results of our study indicate that styrylpyridinium compounds are promising candidates in the development of new antifungal drugs.
The growing level of wastewater as well as pollution of freshwater by various bacteria are essential worldwide issues which have to be solved. In this contribution, nanocrystalline anatase TiO2 films deposited by magnetron sputtering on high-density polystyrene (HDPE) beads were applied as floating photocatalysts for Salmonella Typhimurium bacterial inactivation in water for the first time. Additionally, the photocatalytic degradation of methylene blue dye in the presence of HDPE beads with TiO2 film under UV-B irradiation was investigated. The suitability to adopt such floating photocatalyst structures for practical applications was tested in cycling experiments. The detailed surface morphology, crystal structure, elemental mapping, surface chemical composition and bond analysis of deposited TiO2 films were investigated by scanning electron microscope, X-ray diffractometer and X-ray photoelectron spectroscope techniques. The bacterial viability as well as MB decomposition experiments showed promising results by demonstrating that 6% of bacterial colonies were formed after the first run and only about 1% after the next four runs, which is an appropriate outcome for practical applications. NPN uptake results showed that the permeability of the outer membrane was significantly increased as well.
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