National Repository of Grey Literature 96 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Use of biochemical methods in the study of plant metabolism with emphasis on the defense system
Bělonožníková, Kateřina
As sessile organisms, plants cannot avoid being exposed to various biotic and abiotic stress factors. To defend themselves plants have developed complex and sophisticated defense mechanisms. In agriculture, pesticides are used for plant protection, but they can have undesirable side effects, and therefore attention is being paid to biological control agents. One such agent is Pythium oligandrum, a soil oomycete that has a positive effect on plants at several levels. On the one hand, it secretes elicitins, which stimulate defensive responses and prepare the plant for possible infection (i.e., priming effect), and on the other hand, it produces tryptamine, a precursor of auxin, thus supporting the plant's growth. Furthermore, P. oligandrum directly acts as pathogen mycoparasite or evokes antibiosis, or competition for nutrients and space with other microorganisms. The key research topic of this thesis was the analysis of the biochemical properties of eleven Pythium strains and their impact on plant metabolism. Our results showed that even closely related P. oligandrum strains significantly differ in the content of compounds secreted into the medium, including proteins, amino acids, tryptamine, and hydrolytic enzymes capable of degrading cell walls (endo-β-1,3-glucanase, chitinase, and cellulase),...
Characterization of plum oil and its use in cosmetics
Kaňovská, Zuzana ; Němcová, Andrea (referee) ; Szotkowski, Martin (advisor)
The aim of this bachelor thesis was to characterize plum kernel oil and to explore its possible use in the cosmetics industry. The theoretical part of the thesis is a research on the properties of vegetable oils in general, plum kernel oil and other kernel oils. In the experimental part, the oil was characterized in terms of the profile of fatty acids, phenolic compounds and tocopherols. Body lotion was also prepared, containing plum kernel oil, for which hydration and barrier properties were determined. Pure plum kernel oil and body lotion were tested for antimicrobial activity.
Biologically active substances of the Gotu kola plant
Šumberová, Michaela ; Nábělek, Jakub (referee) ; Zemanová, Jana (advisor)
The Bachelor thesis focuses on the preparation and characterization of the extract of Gotu kola (Centella asiatica). The theoretical part summarizes commonly analyzed groups of biologically active compounds of herbs and introduces potential applications of the extract in food industry. Moreover, an overview of possibly used extraction methods and analytical methods for the evaluation of biologically active compounds of the extract are presented. As for the experiment, the extract of the fresh Centella asiatica herb was prepared by maceration in ethanol and then analyzed by three chosen methods. The total phenolic content of the extract analyzed by the Folin-Ciocalteu test was 0.74 ± 0.08 mgGAE·g-1. As for the quantification of antioxidant activity, the TEAC test was performed and the antioxidant activity of the extract was 289 ± 81 µg·ml-1. The volatiles present in the extract were identified by gas-chromatography mass-spectrometry in combination with solid-phase micro-extraction. Sesquiterpenoid hydrocarbons were the most dominant group of the extract, in which -farnesene (33.28 %), -caryophyllene (25.01 %), and -humulene (20.91 %) were the major compounds.
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 geographical authenticity of Moravian white wines
Horáková, Kristýna ; Křikala, Jakub (referee) ; Diviš, Pavel (advisor)
The aim of this bachelor thesis was to verify geographical autenticity of Moravian white wines based on elemental analysis. This data were completed with the analysis of organic acids, fenolic compounds and atioxidants in wines. There were used two spektrometric methods for the elemental analysis (ICP-MS and ICP-OES). The concentration of organic acids was mesured by Ion chromatography. To determine the concentration of phenolic compounds in wines there was used the high performance liquid chromatography (HPLC-DAD), the content of antioxidants and the total content of phenols was measured on spectrophotometer. In total there were 33 samples of wine from 4 Moravian subregions. For the purpose of determination the samples in groups the dataset was firstly corrected by Grubbs test for remote results. From those data the box plots were created which represents the minimal, maximal and mean concentrations of each measured component. Furthermore the analysis of variance was applied, which picked up 12 statisticly valuable parameters from the whole 47. By appliyng the multidimensional statistical methods (Pearson correlation analysis (PCA) and discriminant analysis (DA)) were compiled mathematical models for the division of Moravian wines according to geographical origin. The success rate of the discrimination test was 96,97%. The cross-validation test showed an 81,82% success rate for classifying unknown samples.
Influence of coffee making process on chemical composition of brewed coffee
Procházková, Kristina ; Divišová, Radka (referee) ; Diviš, Pavel (advisor)
This bachelor thesis deals with the influence of baristic coffee preparations on the chemical composition of the obtained beverage. Teoretical part of this thesis focuses on coffee growing, processing technology and the chemical composition of coffee beans. In the experimental part were measured samples of espresso coffee, samples prepared by moca pot, flip-drip method, filtrated coffee, samples prepared by french-press technique, vacuum pot samples and boiled coffee. The samples were prepared according to the baristic techniques at first and later with adjusted water and amount of coffee so these methods could be compared with each other. This work focuses on the determination of caffeine and acrylamide content by liquid chromatography, validation of HPLC method, determination of total phenolic content by Folin-Ciocalteu reagent, determination of organic acids by ion chromatography, determination of selected macro and micro elements by inductively coupled plasma in optical emission spectrometry and analysis of aromatic substances using gas chromatography. Based on the processed results and compared methods, it was shown that the moca pot had the greatest influence on the content of caffeine, acrylamide, organic acids and total phenolic substances, and the flip-drip with vacuum pot method had the greatest influence on the content of aromatic substances. From a baristic point of view the highest concentration of caffeine was 3689 mg/l in coffee based on flip-drip method, and concentration of acrylamide was 25,4 mg/l in the coffee based on the same method. The highest value of total phenolic content was determined in moka pot to c = 5,23 g/l. Regarding the mineral representation, the mineral decomposition of coffee beans and espresso were compared, and the highest values were reached by potassium, namely the concentration was 577 mg/l per 1 g of mineralized sample, in the cup of espresso the potassium concentration was 2461 mg/l. The highest content of organic acids was determined in the beverage prepared by moca pot, in terms of selected acids, the largest representation had the succinic acid with the concentration 599,8 mg/l. The highest content of aromatic substances was found in coffee from a moca pot and in coffee by flip-drip method. The biggest part was~made by furfuryl alcohol.
Isolation and characterizaation of oil from some types of coffee
Vašků, Barbora ; Hoová, Julie (referee) ; Matoušková, Petra (advisor)
Coffee, extract, oil, phenolic compounds, flavonoids, antioxidant capacity, SPF, critical wavelenght.
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.
Analýza množství extraktivních látek a barvy dřeva dubu zimního
Holčák, Martin
This thesis assesses the experimental findings of the total content of extractives and of the shared content of phenolic substances in wood extracts of the Sessile oak (Quercus petraea) from four different locations in the southern region Pfälzer Wald in the Rheinland-Pfalz Federal Republic of Germany. Moreover, the thesis measures the wood colour in CIE Lab besides focusing only on chemical analysis. The theoretical part outlines general facts about the macroscopic and microscopic structure of the wood (Quercus pertaea). Also, it discusses in detail the issue of colour and chemical composition of wood with a focus on accompanying components. The chapter Methodics describes the process of the entire experiment for the possibility of repeatability of the measurement. The results of this work show mean values of the parameters of the colour L* = 66,7; a* = 7,0; b* = 20,8. Dependence on the total content of the extracts in the wood of the Sessile Oak is not statistically evaluated for these values. The total average content of extracts in wood is assessed at 6,7 % and the content of phenolic substances represents 3,4 %. It is detected that the own colour of wood and also the content of extractives may be affected by the location of growth or even by the position itself within the trunk radius.

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