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Characterization of the genus Plectrantus for use in the food industry
Chmelová, Nikola ; Diviš, Pavel (referee) ; Vítová, Eva (advisor)
The aim of this diploma thesis was to determine the optimal extraction conditions for obtaining an extract from the plant Plectranthus amboinicus. Plectranthus amboinicus is an aromatic herb of the Lamiaceae family containing a large number of bioactive compounds. Because of this, it has a number of biological effects – antimicrobial, anti-inflammatory, antioxidant, analgesic, etc. To maintain the maximum of sensory and nutritionally valuable components of P. amboinicus, a simple maceration of fresh chopped herb was chosen. Maceration was performed under the following conditions: 40 minutes at 40 ° C, solvent 40% ethanol, weight 20 g of herb per 100 ml of solvent. The extract prepared under these optimal conditions was comprehensively characterized in terms of the content of total polyphenols, their concentration was determined to 0,08 ± 0,02 mgGEA·ml-1, which corresponds to 0,40 ± 0,07 mgGEA·g-1 of the plant. The antioxidant activity of the extract was 241,24 ± 29,24 µgTEAC·ml-1 and the radical scavenging activity of ABTS•+ was determined to be 49,29 ± 5,97 %. The antimicrobial activity was verified by the agar well diffusion method. Two types of bacteria were selected for the determination – gram-positive Bacillus cereus, gram-negative Escherichia coli and yeast Candida glabrata. The results showed that the extracts have the highest antimicrobial activity against B. cereus. There were 64 volatile aromatic compounds identified in the extract, with monoterpenes and sesquiterpenes dominating. The obtained results confirm that P. amboinicus, or its prepared extract, has a good potential for use as a new and non-traditional flavor in various foods and delicacies, which can also increase their nutritional value.
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Use and application of natural antimicrobial substances
Dzurická, Lucia ; Byrtusová, Dana (referee) ; Skoumalová, Petra (advisor)
The presented bachelor thesis is focused on the study of antimicrobial activity of plant substances in combination with bacteriocins and the possibility of creating new encapsulated form of supplement which could be used in food and cosmetic products. 5 plant materials were selected: acerola, cinnamon, cloves, orange peel and yacon syrup. Nisin was chosen as the most suitable bacteriocin. In the theoretical part the components with antimicrobial and antioxidant activity are described, such as the materials of plants and animal origin used in this work. Also the possibility of increasing the antimicrobial effect and possible use of natural antimicrobial substances were described. In experimental part, the aqueous extracts of selected plant materials were firstly spectrophotometrically characterized for the content of total polyphenols, flavonoids and antioxidants. Selected substances were encapsulated into liposomes and subsequently preparation of liposomes coated with chitosan was optimized. The particles were tested for size, short and long term stability, encapsulation efficiency and antioxidant activity. Furthermore, the antimicrobial activities of selected components in nonencapsulated and encapsulated form were observed against four strains of microorganisms (Escherichia coli, Micrococcus luteus, Serratia marcescens and Candida glabrata). Also the expected synergisms of the antimicrobial effects of extracts in combination with nisin and prepared particles were observed.
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Analysis of active substances contained in lavender and thyme extracts
Vašíčková, Milada ; Vysoká, Marie (referee) ; Skoumalová, Petra (advisor)
The presented bachelor thesis is focued on active substances contained in lavandula officinalis and common thyme extracts, mainly their possible antimicrobial and antioxidant effects. The theoretical part desrcibes chosen plants, compounds with antimicrobial and antioxidant effects, methods how to obtain and identify said compounds. In the experimental part, aquenous, ethanolic and oil extracts were prepared. Mentioned extracts were spectrophotometrically characterised for total content of polyphenols, total content of flavonoids and antioxidant activity. In conclusion possible applications of extracts in food industry instead of synthetic preservatives and their fotification were discussed.
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TiO2 nanoporous surfaces and their properties
Roček, Vojtěch ; Urbánková, Kateřina (referee) ; Drbohlavová, Jana (advisor)
This thesis is focused on creation nanostructured surfaces of titanium dioxide and the use of photocatalytic activity of these surfaces for antimicrobial applications. The work is divided into nine main chapters, in which the literature search for producing these surfaces, the principle of photocatalysis and their typical specifics was made. These theoretical findings are then used to form such layers, analyzing their chemical and physical properties and practical verification of their antimicrobial activity. This work experimentally verified processes to ensure the increase of antimicrobial activity. The results and findings are discussed in the conclusion.
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Study of natural antimicrobial mixtures and their stabilization
Vejrostová, Petra ; Veselá, Mária (referee) ; Márová, Ivana (advisor)
Present diploma thesis is focused on natural antimicrobial substances. The aim of the experimental part of thesis was testing of antimicrobial activity of selected natural substances in free and encapsulated forms, preparation of particles and monitoring of their long-term stability. Various teas extracts (aqueous, ethanoic and DMSO) and aqueous herbs extracts were used as plant antimicrobial substances. Liposomes and chitosan particles with encapsulated aqueous teas extracts were prepared by ultrasonication. Encapsulation efficiency, size, stability and antioxidant activity for all particles were specified. Consequently, within a two months period, long-term stability for these particles was monitored. Spectrophotometric method for determining total polyphenols was used for evaluating encapsulation efficiency as well as for monitoring of long-term stability. The DLS method was used for determination of size and stability of particles. Antioxidation activity was monitored by using spectrophotometric method using ABTS. For testing antimicrobial activity of various types of teas, herbs extracts and their mixtures and combianitons with lysozyme and antibiotics, broth dilution methods were used while using both Gram positive and Gram negative bacterial test strains. Antimicrobial activity of prepared particles was also monitored, the antimicrobial activity was especially significant with the chitosan particles. Suitable combinations of natural substances whatever with antimicrobial or antioxidation effect either in free or encapsulated form could be used for applications for example in cosmetics industry, food processing or in medicine.
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Analysis of beta-glucans in some fungi
Phan, Huong Tra ; Veselá, Mária (referee) ; Márová, Ivana (advisor)
The main goal of this thesis was to analyse the amount of beta glucans in selected mushroom species. The overall characterization of the composition and content of bioactive compounds in mushrooms was studied too. The theoretical part was focused on description of Fungi, especially the Basidiomycota phyla. The overview of fungal morphology and chemical composition was elaborated. Further, theoretical basis of analytical methods used was introduced. In the experimental part, extracts from selected species of mushrooms (shiitake, oyster mushroom, white champignon, brown champignon and jew’s ear) were prepared. Overall group parameters such as polyphenols, flavonoids, antioxidant activity were determined by spectrophotometry. The amount of beta-glucans in the fungi was measured after enzyme hydrolysis using commercial kit. The content and composition of fatty acids was measured by gas spectrometry. Using emission spectrometry (ICP/OES) the presence of heavy metals was analysed in fungal extracts. Cytotoxicity was tested by MTT test on human cell lines. In the last part the antimicrobial activity against Gram-positive bacterium Micrococcus luteus, Gram-negative Serratia marcescens and yeast Candida labrata was tested. In the thesis, a complex characterization of composition and biological effect of some mushrooms was given.
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Release of active substances from porous structures based on poly(3-hydroxybutyrate) (PHB)
Černeková, Nicole ; Veselá, Mária (referee) ; Kovalčík, Adriána (advisor)
This bachelor thesis deals with the study of the release of active substances from porous structures based on poly(3-hydroxybutyrate) (P3HB). The theoretical part describes the basic characteristics of polyhydroxyalkanoates, their effect on the organism and method of electrospinning. In the experimental part, solutions of poly(3-hydroxybutyrate) in a solvent mixture of dichloromethane and chloroform were electrospun in three different ratios. The morphology of the formed fibrous porous structures was assessed by scanning electron microscopy, based on which the active substance, the antibiotic Levofloxacin, was incorporated into suitable structures. Antimicrobial activity of the antibiotic released from prepared porous structures was tested by the agar diffusion method against gram-negative bacteria Escherichia coli and Serratia marcescens, the gram-positive bacterium Micrococcus luteus and against the yeast Candida glabrata. The results showed a significant antimicrobial effect of the prepared samples against all bacterial cultures, in the case of the culture of yeasts, no zones of inhibition occurred. Next, the course of the active substance release from the prepared electrospun meshes was studied spectrophotometrically depending on the morphological structure. It was found that the active substance was successfully incorporated into electrospun fibers and the course of the drug release depended on the morphology of P3HB electrospun meshes.
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Characterization of organic nanoparticles with encapsulated antimicrobial peptides
Vejrostová, Petra ; Němcová, Andrea (referee) ; Márová, Ivana (advisor)
This bachelor thesis is focused on characterization of particles containing encapsulated antimicrobial enzyme lysozyme. The theoretical part deals with characterization of antimicrobial peptides and their description. Further part of review was focused on lysozyme, the selected representative used in this thesis, its structure, mechanism of action and possible usage. In the experimental part the Hartree-Lowry method was used for lysozyme detection, determination of encapsulation efficiency and for detecting the amount of lysozyme released after incubation in model physiological environment and in model foods. In process of encapsulation the highest amount of lysozyme was packed into 1% chitosan particles, manually prepared alginate particles and into liposomes. During study of stability of particles in model foods as the least stable manually prepared chitosan particles were found. The released lysozyme exhibited changes probably caused by its degradation. The highest influence on particles proved 3% acetic acid. During studying the stability of the particles in artificial digestive fluids as the most unstable manually prepared chitosan particles were found, while alginate particles were the most stable. The thesis also deals with changes in antimicrobial activity of encapsulated lysozyme in prepared particles and after its application into the model environments. A gram-positive bacteria Bacillus subtilis was used in order to test the antimicrobial activity. Antimicrobial tests showed that after encapsulation antimicrobial activity of lysozyme was substantially decreased in most samples. Size and stability of prepared particles was tested using dynamic light scattering.
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Antimicrobial activity of selected natural extracts
Šandová, Lucie ; Veselá, Mária (referee) ; Zemanová, Jana (advisor)
The aim of the bachelor thesis was to determine antimicrobial activity of selected natural extracts, specifically three model extracts made from purple coneflower (Echinacea purpurea) and four commercial extracts – true lavender (Lavandula angustifolia), lemon balm (Melissa oficinalis), echinacea herbal drops (Echinacea purpurea) and echinacea extract (Echinacea purpurea) with ginger, against selected microorganisms. Theoretical part is focused on description of bioactive substances that are found in plants. It also describes extraction methods used for obtaining extracts from plant materials, methods for determining antimicrobial activity and then the use of natural extracts in food and cosmetic industry. In experimental part, antimicrobial effect of the extracts was tested against gram-negative bacteria Escherichia coli, gram-positive bacteria Bacillus cereus and yeast Candida glabrata. For determination of the antimicrobial activity, two methods (hole method and disc diffusion method) were used and compared. The highest antimicrobial activity against selected microorganisms was showed by commercial extract of lemon balm, which contains lot of geraniol and citroneloll. Significant antimicrobial activity had also been shown by commercial extract of true lavender. On the contrary, extracts from Echinacea had not shown any antimicrobial activity against selected microorganisms.
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Antimicrobial activity of carbon-based fillers
Stuchlíková, Olga ; Hermanová, Soňa (referee) ; Voběrková, Stanislava (advisor)
Diplomová práce se zabývá vlivem uhlíkatého plniva na životaschopnost a produkci extracelulárních látek vybrané bakterie Bacillus subtilis (CCM 1999) a kvasinky Yarrowia lipolytica (CCY 29-26-52). Antimikrobiální aktivita těchto částic, přítomných v kultivačním mediu, byla sledována pomocí následujících parametrů: růst daného mikroorganismu, produkce extracelulárních proteinů a v poslední řadě byla monitorována produkce extracelulárních polymerních substancí, které mají úzkou souvislost s tvorbou biofilmu. Suspenze materiálů (0,135 mg/mL) byly připraveny ve dvou rozdílných kultivačních mediích; tzn. živné medium s obsahem glukózy pro Bacillus subtilis a bazální medium s přídavkem Tweenu 80 pro Yarrowia lipolytica, a media byla inokulována příslušným typem mikroorganismu. Experimenty probíhaly po dobu 6 dnů při rychlosti třepání 160 rpm a teplotě 30 °C pro Bacillus subtilis a 28 °C pro Yarrowia lipolytica. Testovány byly celkem tři typy uhlíkatého nanomateriálu, získané z Katedry anorganické chemie, Vysoké školy chemicko-technologické v Praze. Tyto materiály specifikované jako materiál “A”, “B” a “C” se navzájem lišily velikostí částic a stupněm oxidace. Na základě skríningových studií byla vybrána koncentrace testovaného materiálu 0,135 mg/mL a rychlost třepání 160 rpm. Metodou měření optické hustoty vzorku při 600 nm byly sestaveny a porovnány růstové křivky obou mikroorganismů v přítomnosti testovaných nanočástic po dobu 5 dní. Tímto způsobem bylo zjištěno, že přítomnost nanočástic v mediu nemá velký vliv na růst zkoumaného mikroorganismu. Tato metoda, je však pouze orientační, protože se nevyhneme chybě díky přítomnosti mrtvých buněk. Dále byla testována produkce celkových a extracelulárních proteinů daným mikroorganismem v přítomnosti testovaných nanočástic. Nebyla však pozorována výrazná odchylka hodnot od hodnot kontrolního vzorku, který neobsahoval testovaný materiál. Na základě metod počítání kolonií (Bacillus subtilis) a buněk (Yarrowia lipolytica) byly určeny ztráty životaschopnosti mikroorganismu ve 3 časech (6, 48 a 144 hodin); v kratším časovém intervalu byl růst spíše podporován. Dále byla monitorována produkce extracelulárních polymerních substancí (EPS), tedy proteinů, redukujících substancí a polysacharidů. Tyto látky byly vylučovány daným mikroorganismem do prostředí v průběhu 24 hodin. Bacillus subtilis produkoval EPS ve větší míře než Yarrowia lipolytica. Předpokládáme, že produkce EPS by mohla souviset s tvorbou biofilmu, který chrání buňky před toxicitou nanočástic.
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