National Repository of Grey Literature 32 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
Sulfates as phase II metabolites of natural phenolic compounds
Hetman, Anastasiia ; Mladěnka, Přemysl (advisor) ; Siatka, Tomáš (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Anastasiia Hetman Supervisor: Assoc. Prof. Přemysl Mladěnka, PharmD., Ph.D. Co-supervisor: Assoc. Prof. Kateřina Valentová, Ph.D. Title of diploma thesis: Sulfates as phase II metabolites of natural phenolic compounds Natural monophenolic compounds, which both occur in plants and are formed during gut microbiota metabolism of polyphenols, are absorbed and pass through phase II metabolism. This results in the formation of various conjugated metabolites, such as sulfates, whose biological activity was not studied as yet. This work focused on the preparation and isolation of pure sulfated metabolites of phenolic compounds, namely 4- methylcatechol, protocatechuic, homoprotocatechuic, and 2,3,4-trihydroxybenzoic acid, and phloroglucinol, using the aryl sulphotransferase from Desulfitobacterium hafniense. As a result, two sulfated products of sufficient purity were prepared, namely 4- methylcatechol-O-sulfate (an inseparable mixture of 4-methylcatechol-2-O-sulfate and 4- methylcatechol-1-O-sulfate) and phloroglucinol-O-sulfate. Their antioxidantactivity was evaluated and compared with the activity of the parent compounds using the following six in vitro tests: DPPH (1-diphenyl-2-picrylhydrazyl) and...
Secondary metabolites and their utilisation in Urtica dioica agg.
Pekařová, Michaela ; Urfus, Tomáš (advisor) ; Hojka, Jakub (referee)
Stinging nettle (Urtica dioica) is a very well-known taxon of genus Urtica, but still its taxonomy is not satisfactory resolved. An obvious reason of taxonomic obscurity of entire aggregate is enormous morphological variation. Polyploidization significantly contributes to this variability. Polyploidy probably is a reason of successful expansion of tetraploid cytotype in synanthropic habitats. Urtica dioica is rich in secondary metabolites, especially fatty acids, phenolic acids and flavonoids. Secondary metabolites are isolated for various purposes. They are widely applied especially in pharmacy and subsequently used for various medications. Despite the undoubtful economic importance a linkage between secondary metabolites composition and polyploidy has not been studied yet.
Study of redox reactions and adsorption of 4-nitrophenyl triazole labeled nucleosides and cresols on boron doped diamond electrodes for development of electroanalytical methods
Vosáhlová, Jana ; Schwarzová, Karolina (advisor) ; Havran, Luděk (referee) ; Navrátil, Tomáš (referee)
In this work, the application of boron-doped diamond electrodes with various surface pre- treatment were tested on selected oxidizable and reducible model compounds, specifically para and ortho cresols and 2'-deoxycytidine and 7-deazaadenosine labeled by 4-nitrophenyl triazole. The aim of the study was the investigation of electrochemical and adsorptive processes with respect to the development of electroanalytical methods of detection of the selected compounds, or utilization of boron-doped diamond electrodes as detectors in liquid-flow systems. Cresols were used as the model oxidizable compound. On O-terminated and polished boron- doped diamond electrodes, cresols provide oxidation signal owing to their oxidation to methylphenoxy radical at comparable potentials as on other carbon-based electrodes used as a reference in this work, i.e., glassy carbon electrode, pyrolytic graphite electrode, and carbon paste electrode. These carbon electrode materials show relatively high propensity to adsorption of reaction products, while such adsorption is minimal on boron-doped diamond. In situ anodic activation allows for a rapid regeneration of boron-doped diamond surface prior to each scan. A differential pulse voltammetric method that was developed with a detection limit of 0.61 mol∙l-1 to 2.97 mol∙l-1...
Influence of beer protein on foam stability
Benda, David ; Štursa, Václav (referee) ; Pořízka, Jaromír (advisor)
This bachelor thesis deals with the influence of beer proteins, phenolic compounds, bitterness and selected metal ions on beer foam stability. The theoretical part describes beer foam from the physical aspect, beer foam stability and its measurement and the factors that positively or negatively influences the stability and quality of the beer foam. In the theoretical part are described selected proteins that influence beer foam. In theoretical part is described the origin and technological significance of proteins. The experimental part is dedicated to the measurement of beer foam stability with the NIBEM method, the analysis of total protein content, the analysis of total phenolic content, bitternes and element analysis of beer samples. Measured data indicated correlations between protein content, phenolic compounds content, bitterness and metal ions with the beer foam stability. The results show that proteins and phenolic compounds as isolated parameters don’t essentialy affect the beer foam stability. It was found out, that bitterness as isolated parameter influences the beer foam stability the most.
Chemical composition of wine produced from PIWI cultivars
Michálková, Kateřina ; Vítová, Eva (referee) ; Pořízka, Jaromír (advisor)
This diploma thesis deasl with the chemical charakterization of wine from selected PIWI varieties. The theoretical part describes the general origin and reason for breeding PIWI varieties, a closer characterization of selected three PIWI varieties, Johaniter, Hibernal and Solaris. The next part is devoted to the description of analytical methods that were used to determine the chemical characteristics. The experimental part is developed to the determination of chemical characteristics, namely general characteristics such as alcohol, total phenols, phenolic substances, volatile substances and elemental composition. The results show that are differences between wines from selected PIWI varieties in therms of chemical composition. The most represented organic acid was in the range of 735,1-1286,2mg/l malic acid. This was followed by acetic in the range of 100-400mg/l. The antioxidant activity was determined in the range of 0,2988-0,9683 mmol/l of Trollox and content of total phenols 273,5-390,3mg/l. Of the phenolic substances, gallic acid was the most represented, ranging from 6,9-13,9mg/l. As another, abundant phenolic substances, catechin in the range of 1,6-6,0mg/l was detected. Of the determined elements, phosphorus in the range of 165,4-450,5mg/l was the most represented. Representatives of ethyl ester, ethyl acetate, decanoic acid ethyl acetate and hexanoic acid ethyl ester, were detected as the most abundant volatiles. From the measured data it was evident that wines from PIWI varieties different from standard varieties, especially in the profile of aromatic substances.
Detoxification of coffee sediments by oxidation processes
Maňáková, Helena ; Pořízka, Jaromír (referee) ; Diviš, Pavel (advisor)
This bachelor thesis deals with the detoxification of used coffee grounds by the oxidation processes. The theoretical section describes the characterization of coffee beans and used coffee grounds. Furthermore, this section describes the valorisation of coffee grounds, especially its application as a fertilizer. The final part of the theoretical section focuses on the characterization of phenolic compounds, which are responsible for toxic properties of used coffee grounds, and analytical methods are described, which include UV–VIS spectrophotometry and high–performance liquid chromatography. The aim of the experimental part is the sample preparation, the application of the effective detoxification process and the analysis of the detoxificated used coffee grounds, focusing on the content of phenolic compounds. At the end of the experimental part, data processing is described. Three types of coffee grounds were used for determination of phenolic compounds: raw, defatted and the third type was defatted and simultaneously hydrolysed. High amounts of phenolic acids were identified in every sample, especially the gallic, ferulic, chlorogenic and caffeic acid. After an oxidizing agent was applied, positive detoxification of every sample of used coffee grounds was confirmed. For the most effective and most economical oxidation, a 1% oxidizing agent was chosen, which after a 10–minute oxidization efficiently reduced the content of the phenolic compound.
Chemical and sensory characterization of cider made from apple cultivars ordinarily grown in Czech republic
Strapcová, Zuzana ; Vítová, Eva (referee) ; Pořízka, Jaromír (advisor)
This master thesis deals with the investigation of selected chemical and sensory characteristics of ciders, which were made from four selected apple varieties. The theoretical part describes the chemical composition of apples, cider, the technology of production and production in the world. The next section describes the analytical methods used to determine chemical characteristics not only in ciders but also in other alcoholic beverages. The experimental part focuses on the determination of chemical characteristics such as the content of organic acids, carbohydrates, total phenolic content, alcohol antioxidant activity and elemental composition. The purpose of the work was to find out how different varieties differ in chemical composition. The produced ciders were subjected to sensory analysis to evaluate the selected cider sensory parameters, which were in the natural state and with the addition of carbon dioxide. The results show that ciders of different varieties differ in chemical composition. Malic acid was the most cider's abundant of the organic acids in the range of 2759 – 4411 mg·l-1. Another acid represented was lactic acid in the range of 166,2 – 288,1 mg·l-1. The glucose content of each cider was determined between 845,3 – 1159,8 mg·l-1and fructose 32,6 – 406,7 mg·l-1. Potassium 944,29 – 1073,98 mg·l-1 was the most represented of all elements. The total phenolic content was determined to be in the range of 164,2 – 214,1 mg of GAE·l-1and the antioxidant activity of 0,192 – 0,318 mg·l-1. These differences in chemical composition were also reflected in sensory evaluation. According to the overall assessment, the best cider was made from the Granny Smith variety, which contained the most organic acids and carbohydrates. It has been found that by adding carbon dioxide, sensory parameters such as colour, taste and smell are altered.
Influence of kitchen treatments on the content of phenolic substances in parsley (Petroselinum crispum)
The Master's thesis deals with the determination of the total content of phenolic compounds contained in garden parsley (Petroselinum crispum). Specifically, the influence of selected kitchen treatments (drying, boiling) on the content of phenolic compounds of garden parsley was monitored in the following three varieties: Atika, Hanácká, Olomoucká. First, the total polyphenol content was determined by spectrophotometry using Folin-Ciocalteau reagent in fresh parsley extract, further samples were dried and boiled. It was always done separately for root and stem. Thereafter, specific representatives of the phenolic compounds were identified using high performance liquid chromatography from the lyophilized material. The highest concentration of phenolic compounds was found in the dried parsley stem in case of all varieties. The highest content of specific phenolic compounds - apigenin, kaempferol, luteolin was found in the Atika variety, and also in the stems of all the mentioned varieties.
Biologically active compounds in uncommon vegetables
My bachelor thesis dealed with determination of content of some phenolic compounds in some rare sorts of vegetable like Amaranthus tricolor, Chrysanthemum coronarium, Brassica rapa var. komatsuna, Brassica rapa ssp. japonica var. mizuna and mibuna, Brassica juncea. These uncommon species belonged to the asian leaf vegetable. At the present time these species are restrained over the whole world. Besides vitamins, these species of leaf vegetable contain also phenolic compounds like flavonoids, which reveal significant biological activity with positive effects on human health. The above mentioned sorts of vegetable were cultivated both on the experimental field on the open air and also in glasshouse. The content of phenolic derivatives was determined by high-performance liquid chromatography. In the selected plants were found these dominant compounds: Amaranthus tricolor contained derivatives of caffeic acid and rutin, in Chrysanthemum coronarium chlorogenic acid, dicaffeoyl acid and dicaffeoyl-succinylquinic acid. In the plants Brassica rapa var. komatsuna and Brassica juncea were determined derivatives of flavonols and phenolic acid, in varieties mizuna and mibuna derivatives of flavonols, phenolic acid and indols. Significant differences in the content of studied compounds was found between the plants cultivated under open air and in glasshouse. The plants cultivated under the open air have significantly higher content of studied compounds than those cultivated in glasshouse.
Ověření vlivu rozpustných fenolických látek na aktivitu extracelulárních enzymů v rašeliništích
The aim of the study was to verify the influence of the soluble phenolic compounds on the activity of extracellular enzymes. We tested the effect of aerobic and anaerobic conditions and addition of soluble phenolic compounds on potential activity of extracellular enzymes in two laboratory experiments. The results showed, that potential activities of oxidative extracellular enzymes such as phenol oxidase and peroxidase did not decline in anaerobic incubations, and have no oxygen requirement. Potential activities of hydrolytic enzymes was not inhibited by phenolic compounds and are oxygen related or have no oxygen relationship. No negative relationship between hydrolytic enzymes and phenolic compounds was observed. In summary, our results do not support the ''enzymatic latch'' hypothesis.

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