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The aim of this work was to find the correlation between the content of ergosterol in fungi membrane and the action of the hop essential oil, myrcene and humulene on its properties. To reach this goal, the monolayers and bilayers composed of phosphatidylcholine, phosphatidyethanol amine and ergosterol, differing in the concentration of sterol, were used as model membrane systems. The impact of the essential oil and its major terpenes on one component ergosterol film was also investigated. It was found that pure isolated terpenes, in contrast to the hop oil being the mixture of them, do not incorporate into pure ergosterol membrane, however, they cause the loss of monolayer material from the interface. These results are in contrast to the effect of these terpenes on phospholipid films reported previously and they may suggest a strong effect of ergosterol on the behavior of terpenes in the mixed systems. Surprisingly, for model membranes, the effect of myrcene was qualitatively similar to the effect of the hop oil and ergosterol was found to regulate the incorporation of both these substances into the film. In contrast, very strong correlation between ergosterol content and the action of humulene was found. Namely, the ability of humulene to change model membrane properties was found to increase with ergosterol concentration. Additionally, the differentiating effect of ergosterol on humulene action in membranes was much more pronounced than for myrcene or the hop oil. Interestingly, at the highest ergosterol level the influence of humulene was even stronger than the effect of the hop oil. This is very important finding suggesting that ergosterol may regulate the sensitivity of particular membrane to the impact of humulene. Summarizing, ergosterol substantially differentiates the effect of the hop oil, myrcene and humulene on the lipid systems and it can be the molecule important for antifungal effect of the essential oil and terpenes., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Bisphenols are the environmental pollution of a highly harmful, but different in their magnitude, influence on the living organisms. Among various aspects of the toxicity of these compounds their effect on the red blood cells is intensively investigated. The aim of this work was to compare the effect of bisphenol A (BPA), bisphenol S (BPS) and bisphenol F (BPF) on model erythrocyte membranes and to get insight into the origin of the differences in the harmful effect of these substances on cells. Thus, the influence of bisphenols on multicomponent Langmuir films imitating the outer leaflet of erythrocyte membrane was thoroughly analyzed. An important step of the experiments were the studies on the effect of bisphenols on the films composed from particular erythrocyte membrane lipids. It was confirmed that both BPA and BPF affect model lipid systems more strongly than BPS, by changing their condensation, ordering, stability and morphology. However, the most essential conclusion was that BPA acts on the erythrocyte lipids more selectively than BPS and BPF and the influence exerted by this molecule is more strongly determined by the membrane composition. It was also suggested that cholesterol may act as the molecule of a decisive role from the point of view of the magnitude of the incorporation and the effect of BPA and BPF on membrane. Thus, the level of bisphenols toxicity to erythrocytes may depend on the concentration of cholesterol in their membranes., Competing Interests: Declaration of Competing Interest The authors declare that there are no conflicts of interest., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Antifungal and herbicidal activity of terpenes, being the components of the essential oils, is directly related to the incorporation of these compounds into cellular membranes. Thus, the differences in the lipid composition of various pathogenic membranes may be the factor determining the activity of these molecules. One of the class of lipids, which form the membrane environment are sterols. The aim of this work was to compare the effect of two terpenes: terpinen-4-ol and eucalyptol on the monolayers formed by ergosterol and β - sitosterol, which are the components of fungi and plant membranes, respectively. The modifications in the sterol monolayer properties were investigated in the surface pressure-area measurements and penetration studies as well as in a micrometer scale (Brewster angle microscopy experiments) and in nanoscale (GIXD technique). It was evidenced that although at higher surface pressure the terpene molecules are in part removed from the interface, they are able to substantially modify the condensation, morphology and molecular organization of the sterol film. It was also found that the incorporation of terpenes into sterol films is comparable for both sterols, however, β - sitosterol monolayers properties are affected more strongly than ergosterol films. Finally, the analysis of the results of the studies performed on model membrane systems and the results of antimicrobial studies reported in literature, enabled us to suggest that the activity of terpenes depends on the membrane composition and that the sterol concentration may be important from the point of view of antifungal effect of terpinen-4-ol and eucalyptol., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Many plant-derived compounds possess antimicrobial, antioxidant and even anticancer activities. Therefore, they are considered as substances that can be used instead of synthetic compounds in various applications. In this work, the essential oil from hop cones was extracted and analyzed, and then its effects on model bacteria membranes were studied to verify whether the hop essential oils could be used as ecological pesticides. The experiments involved surface pressure-area measurements, penetration studies and Brewster angle microscopy (BAM) imaging of lipid monolayers as well as hydrodynamic diameter, zeta potential, steady-state fluorescence anisotropy and Cryo-Transmission Electron Microscopy (cryo-TEM) measurements of liposomes. Finally the bactericidal tests on plant pathogen bacteria Pseudomonas syringae pv. lachrymans PCM 1410 were performed. The obtained results showed that the components of the essential oils from hop cones incorporate into lipid monolayers and bilayers and alter their fluidity. However, the observed effect is determined by the system composition, its condensation and the oil concentration. Interestingly, at a given dose, the effect of the essential oil on membranes was found to stabilize. Moreover, BAM images proved that hop oil prevents the formation of a large fraction of a condensed phase at the interface. Both the studies on model membranes as well as the in vitro tests allow one to conclude that the hop essential oil could likely be considered as the candidate to be used in agriculture as a natural pesticide., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Optimum conditions for the reversed-phase liquid chromatographic separation of uranium as U(VI)-F(-)-(5-Br-PADAP) [5-Br-PADAP is 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol] ternary complex on the end-capped C18 column were evaluated. The developed sensitive, selective and versatile method allows to determine uranium in the wide concentration range 0.2-120.0 mug ml(-1) (detection limit, DL, is 0.15 mug ml(-1) for 20 mul loop). Solvent mixture, acetonitrile+water (65+35, v/v) containing fluoride in concentration 3x10(-3) mol l(-1) (pH 5.5) was used as eluent. Double action of fluoride present in eluent - as stabilising agent of the ternary system and modifier of the stationary phase was evaluated. In order to prove appearance of the modifying effect of fluoride on the stationary phase the new chromatographic probe - system Zr(IV)-(5-Br-PADAP)/Zr(IV)-F(-)-(5-Br-PADAP) was introduced as a tool for the detection of F(-) presence on the surface.

Four different hyphenated techniques: microbore reversed phase (RP) HPLC-ICP MS, CZE-ICP MS, RP HPLC-ES MS and CZE-ES MS were investigated for the characterization of metallothionein-metal complexes under neutral pH conditions. Particular attention was given to the differentiation between metallothionein and artifact signals, identification of mixed-metal complexes, and the validity of the molecular mass as the identification parameter of the different MT iso- and sub-isoforms. Despite the similar morphology of chromatograms and electrophoregrams mass spectrometry revealed different origin of the apparently corresponding peaks. The performance of the four above mentioned techniques was characterized using the example of rabbit liver MT-1 preparation. Reversed-phase HPLC with post-column acidification prior to ES MS was judged to be the most versatile technique for the characterization of metal complexes with metallothioneins but other techniques offer valuable auxiliary information.