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Hodnocení antifungální aktivity esenciálních olejů prostřednictvím vybraných laboratorních metod
KRATOCHVÍLOVÁ, Viola
The utilization of the antifungal activity of essential oils in the storage of vegetables and food is becoming an increasingly monitored and researched topic currently. The antifungal effects of essential oils offer the possibility of extending the shelf life of food and reducing losses caused by fungi and other microorganisms. These are natu-ral substances that are non-toxic to humans or the environment. Essential oils have recently gained popularity due to their diverse applications, not only in industries such as cosmetics and pharmaceuticals but also in our households. This popularity supports the interest in their use in food as a natural means of reducing fungal occurrence and extending the shelf life of food. The aim of this thesis is to compare the antifungal effectiveness of selected essential oils against isolated microscopic fungi from root vegetables and to compa-re selected methods used for evaluation. The literature review presented in this the-sis summarizes the current knowledge in the area of the antimicrobial effects of essential oils, which offer the possibility of extending the shelf life of food and re-ducing losses caused by fungi and other microorganisms. In the practical part, the four most common morphotypes of microscopic fungi (Fusarium sp., Paecilomyces sp., Trichoderma sp., and Chalaropsis thielavioides) are isolated from root vegeta-bles, which are used in testing the antifungal activity of selected essential oils (ci-tronella, clove, dill, peppermint, cinnamon, and thyme) using the disk diffusion method and the micro-dilution method. The results of the disk diffusion method and the microdilution me-thod slightly differ from each other. The inhibition of essential oils appears slightly higher in the microdilution method, likely due to the presence of volatile com-pounds that more effectively spread within the enclosed space of the microplate, thus exerting a stronger influence on the growth of the tested fungi. However, the three most effective oils are consistent in both methods. Specifically, these are the oils of dill, thyme, and cinnamon. Similarly, the least effective oil is consistent in both methods - peppermint oil.
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The effect of antimicrobial peptides on Saccharomyces cerevisiae and other yeast species
Makarova, Anna-Marie ; Hodek, Petr (advisor) ; Malcová, Ivana (referee)
The increased use of antibiotics, antifungal agents and disinfectants in the last decades has resulted in development of microbial resistance to these drugs. Candida species are the fourth most common cause of hospital-acquired bloodstream infection and kill 40% of those patients. Natural antimicrobial peptides are promising candidates for the development of new agents to treat yeast and bacterial infections, as their presumed mechanism of action differs significantly from the mechanism of action of current drugs. This work is focused on several peptides isolated from the venom of wild bees and their synthetic analogues and the identification of the most effective ones against non-pathogenic Saccharomyces cerevisiae and several pathogenic Candida species. Antifungal activity of eight cationic antimicrobial peptides was tested and compared under various conditions. The overall susceptibility of pathogenic yeast species to currently used antifungal drugs and the antimicrobial peptides was screened with the aim to identify potential synergistic and species-specific effects. The effect of antimicrobial peptides on membrane potential was measured by a fluorescent probe (diS-C3(3)), and the relative hyperpolarization of plasma membrane was shown for each peptide. The effect of antimicrobial peptides on...
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Mechanisms and mode of action of essential oils on fungi
Ježková, Tereza ; Koukol, Ondřej (advisor) ; Čmoková, Adéla (referee)
Essential oils are volatile compounds from plants with a wide range of effects. Many of them exhibit antifungal activity. As the resistance of pathogenic fungi to antimycotics is increasing, finding new antifungal agents for the treatment of fungal infections is highly desirable. In order to use essential oils for the production of new drugs, it is necessary to know the exact mechanism of their action. Although it is known a lot about the effects of essential oils on fungi, the particular target in a cell is not always described. In this thesis I summarize the present knowledge about the mechanisms of actions on fungi. I gradually deal with effects of essential oils on cell wall, plasma membrane, mitochondrion, nucleus, quorum sensing, virulence factors, mycotoxin production and fungal development. Generally essential oils do not act on one structure but affect multiple structures and processes at the same time. In the last chapter I mention possible directions for further research of these substances. Key words: essential oils, fungi, antifungal activity, mechanism of action, mode of action
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The effect of antimicrobial peptides on Saccharomyces cerevisiae and other yeast species
Makarova, Anna-Marie ; Hodek, Petr (advisor) ; Malcová, Ivana (referee)
The increased use of antibiotics, antifungal agents and disinfectants in the last decades has resulted in development of microbial resistance to these drugs. Candida species are the fourth most common cause of hospital-acquired bloodstream infection and kill 40% of those patients. Natural antimicrobial peptides are promising candidates for the development of new agents to treat yeast and bacterial infections, as their presumed mechanism of action differs significantly from the mechanism of action of current drugs. This work is focused on several peptides isolated from the venom of wild bees and their synthetic analogues and the identification of the most effective ones against non-pathogenic Saccharomyces cerevisiae and several pathogenic Candida species. Antifungal activity of eight cationic antimicrobial peptides was tested and compared under various conditions. The overall susceptibility of pathogenic yeast species to currently used antifungal drugs and the antimicrobial peptides was screened with the aim to identify potential synergistic and species-specific effects. The effect of antimicrobial peptides on membrane potential was measured by a fluorescent probe (diS-C3(3)), and the relative hyperpolarization of plasma membrane was shown for each peptide. The effect of antimicrobial peptides on...
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