National Repository of Grey Literature 27 records found  1 - 10nextend  jump to record: Search took 0.00 seconds. 
The influence of cytochrome b5 on naphthalene oxidation catalyzed by human cytochrome P450 1A2
Stránský, Jaroslav ; Martínek, Václav (advisor) ; Moserová, Michaela (referee)
Cytochromes P450 (CYP) form a crucial group of oxidoreductase-class enzymes participating in the biotransformation of numerous endo- and exogenous compounds (xenobiotics). A negative aspect to the activity of this enzyme, however, can be the bioactivation, a process during which an originally only slightly toxic compound is transformed into a substance of much higher toxicity. Cytochrome P450 has therefore long been standing at the forefront of biochemical and medicinal interest. For the proper function of cytochrome P450 a supply of electrons into a catalytic cycle is necessary. This is usually taken care of by NADPH:cytochrome P450 oxidoreductase. Cytochrome b5, an enzyme present in the membrane of the endoplasmic reticulum of eukaryotic cells along with NADPH:cytochrome P450 oxidoreductase and cytochrome P450, however, can also act as an alternative electron donor. The participation of cytochrome b5 in the catalytic cycle of cytochrome P450 have a potential to modulate this cycle. Over the course of evolution, many isoforms of cytochrome P450 have developed, each possessing different substrate specifity, catalytic properties, distributions within various tissues etc. This bachelor thesis is focused on the isoform 1A2 (CYP1A2) which represents nearly 10 % of all human hepatic cytochrome P450s....
Biotranformation of fenbendazole in soya (Glycine max)
Martínková, Lenka ; Raisová Stuchlíková, Lucie (advisor) ; Matoušková, Petra (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Biochemical Sciences Candidate: Bc. Lenka Martínková Supervisor: RNDr. Lucie Raisová Stuchlíková, Ph.D. Title of diploma thesis: Biotransformation of fenbedazole in soya (Glycine max) Veterinary drugs are used in large amounts in modern husbandry for treatment and prevention of diseases in animals. Anthelmintics administered to animals enter into environment primarily through its excretion in faeces or urine. Following excretion, drugs may persist in the environment and impact non-target organisms. Plants are able to uptake xenobiotics, including drugs, and detoxify them via biotransformation. However, only drug biotransformation into non-toxic and stable metabolites and their consequent accumulation in plants represent drug detoxification. For that reasons, knowledge of biotransformation pathways of drug in plants is very important. Soybean plants, eventually seeds, are further used in agriculture as feed for cattle and absorbed anthelmintics including their metabolites can enter the food chain. The results showed that fenbendazole entered plant and enzymatic systems of plant were able to biotransform fenbendazole via several reactions. We found differences in the metabolites between the roots, leaves, seeds and pods of soybean.
The effect of tyrosinkinase inhibitors vandetanib and lenvatinib and cytotoxic alkaloid ellipticine on biotransformation enzymes
Baráčková, Petra ; Dračínská, Helena (advisor) ; Václavíková, Radka (referee)
In recent years, tyrosine kinase inhibitors have been widely used for the treatment of certain tumors as so-called targeted therapy. Many studies are concerned with their metabolism and the role of enzymes in the biotransformation process, but very little is known about the impact of tyrosine kinase inhibitors on the expression and activity of biotransformation enzymes. Nevertheless modification of the expression and activity of enzymes may cause adverse interactions of co-administered drugs and their negative impact on the human body. This diploma thesis studies the effect of tyrosine kinase inhibitors vandetanib and lenvatinib and cytotoxic alkaloid ellipticine on biotransformation enzymes in a rat model organism in vivo. The aim was to characterize the effect of the investigated compounds on gene expression, protein expression and activity of cytochromes P450 (CYP) 1A1, 1A2 and 1B1 and flavin-containing monooxygenases FMO1 and FMO3 in renal and hepatic microsomes. Microsomes and RNA were isolated from kidneys of control rats and the pretreated rats. Western blot and immunodetection was used to compare the protein expression levels of studied enzymes in kidney and liver. By reverse transcription, cDNA was prepared from isolated RNA and used as a template for quantitative PCR to compare the...
Biotransformation of monepantel in plant (Campanula rotundifolia, Plantago lanceolata)
Crhová, Anna ; Raisová Stuchlíková, Lucie (advisor) ; Vokřál, Ivan (referee)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Biochemical Sciences Candidate: Bc. Anna Crhová Supervisor: RNDr. Lucie Stuchlíková Raisová, Ph.D. Title of diploma thesis: Biotransformation of monepantel in plants (Campanula rotundifolia, Plantago lanceolata) Anthelmintics are veterinary drugs used to eliminate disease caused by parasitic worms. Monepantel (MOP) is a representative of amino-acetonitrile derivatives. This relatively new group of drugs is effective on helminthic strains, which are resistant to classic therapy (benzimidazoles, makrocyklic lactones, imidazothiazoles). Due to high consuption of these drugs, it is important to find out their fate in the exposed organisms. Anthelmintics are in contact with the environment and they can affect terrestrial and aquatic organisms. Their various forms can be accumulate in plants. These plants can be eaten by the animal, which may lead to development of resistance in helminths. In addition, the physiology of plants and animals may be disrupt and, consequently, biodiversity loss may occur. The aim of this study was to determine the biotransformation processes occurring in ribwort plantain (Plantago lanceolata) and harebell (Campanula rotundifolia) after low concentrations of MOP. Suspensions of both plants cells...
Disposition of New Synthetic Drugs in The Organism. Pharmacokinetics and Biotransformation Study. Toxicological Detection in Biological Materials.
Židková, Monika ; Balíková, Marie (advisor) ; Šustková, Magdaléna (referee) ; Šanda, Miloslav (referee)
The object of this thesis was the study on the pharmacokinetics and biotransformation of selected abused new synthetic drugs, specifically belonging to cathinone and aminoindane groups, in experimental rats. This work consisted of two parts: a biotransformation study of mephedrone, methylone, 5,6-methylenedioxy-2- aminoindane (MDAI) and a distribution profile study of mephedrone, methylone, MDAI and naphyrone. This document is presented as a commentary to the original papers, which were published in peer reviewed journals. The samples of blood and tissue (brain, lungs, liver) were taken at specific times after a subcutaneous single bolus dose of the studied drugs. The urine samples for the biotransformation studies were collected over a 24-hour period following the sc. dose. The LC/HRMS method was used for metabolite detection and quantitative analysis. Our findings not only included testing metabolites of the aforementioneddrugs against the synthesized reference standards, but also discovering previously unknown metabolites of these drugs. Ten phase I and five phase II metabolites aside from the parent drug were identified in urine after mephedrone administration by comparison of their spectra against those of reference standards and/or MS2 spectra of previously identified metabolites. The main...
Enzymatic modifications of bioactive flavonoids
Rydlová, Lenka ; Tesařová, Eva (advisor) ; Wimmer, Zdeněk (referee)
Extract from milk thistle (Silybum marianum (L.) Gaertn., synonym Carduus marianus L., Asteraceae) silymarin contains among others primarily bioactive flavonolignans. They have hepatoprotective and antioxidative effects and also anticancer, chemoprotective, dermatoprotective and hypocholesterolemic activity. This thesis focuses on the preparation of metabolites of the second phase of biotransformation unexplored flavonolignans 2,3-dehydrosilybin (DHSB), silychristin (SCH), 2,3-dehydrosilychristin (DHSCH). Pure sulfated derivatives were prepared using aryl sulfotransferase from Desulfitobacterium hafniense and p-nitrophenyl sulfate (p- NPS) as a donor. Flavonolignans yield exclusively monosulfates at the position C- 20 (C-19 in the case of silychristin and 2,3-dehydrosilychristin), except for 2,3- dehydrosilybin that gives also the 7,20-disulfated derivatives. For all samples were made antioxidant tests - DPPH assay (the highest activity had 2,3-dehydrosilychristin sulfate: IC50= 7,87 µM), Folin-Ciocalteau reduction assay (the highest activity had 2,3-dehydrosilychristin: 1,58 ekvivalents of gallic acid), ABTS+ scavenging (the highest activity had silychristin: 1,50 ekvivalents of vitamin C), inhibition of microsomal lipid peroxidation (the highest activity had 2,3-dehydrosilybin: IC50 = 10,6 µM),...
Morphine alkaloid metabolism in bacteria
Zahradník, Jiří ; Kyslík, Pavel (advisor) ; Lichá, Irena (referee)
Morphine alkaloids and their derivatives are pharmaceutically important substances. Huge production and consumption of these compounds predetermines them to be significant pollutants in the environment. Some of them have been detected in surface waters. The aim of this study was to characterize effects of morphine alkaloids on the physiology of three model organisms: Agrobacterium sp. R89-1, Escherichia coli XL-1 (Blue), and Raoultella sp. kDF8, and elucidation of the mechanisms leading to toxicity. The biotransformation potential and utilization ability were characterized for model organisms. It was demonstrated that the microorganism Agrobacterium sp. R89-1 is capable of rapid biotransformation of codeine to its 14-OH derivatives. The manifestation of morphine compounds toxic effects for the strain R89-1 is the highest. In contrast, microorganism Raoultella sp. KDF8 is able to utilize codeine as a carbon and energy source. The accumulation of 14-OH-derivatives was not observed. Escherichia coli XL-1 (Blue) is not able to biotransform or utilize codeine. Α, β-unsaturated ketones (morphinone, codeinone, 14-OH-morphinone and 14-OH-codeinone) were found as a most toxic intermediates of codeine metabolism. Bacterial cell growth (strains R89-1 and KDF8) in the presence of codeine is characteristic with...
The influence of xenobiotic metabolizing enzymes and transporters on the incidence of colorectal cancer and chemotherapy outcome
Krus, Ivona ; Souček, Pavel (advisor) ; Králíčková, Milena (referee) ; Hodis, Jiří (referee)
Introduction: Colorectal cancer (CRC) is one of the most frequent malignancies and affects approximately 5% of worldwide population. More than 75% of CRC cases represent sporadic forms. Susceptibility to nonhereditary CRC is significantly influenced by polymorphisms and mutations in low-penetrance genes. Variations in biotransformation and DNA repair genes may result in acumulation of toxins and DNA damage in cells leading to the development of cancer. Furthermore, different gene expression profiles of membrane transporters affecting the accumulation of anticancer drugs in tumour cells, e.g. ABC drug transporters, may largely influence inter-individual variability in drug response and chemotherapy outcome. The aim of this study was to evaluate the role of genetic and lifestyle factors in the risk of onset and progression of colorectal cancer. This study followed selected genetic alterations in xenobiotic-metabolizing enzymes (CYP1B1, GSTM1, GSTT1, GSTP1, NQO1 and EPHX1) and genes involved in response to DNA damage (CHEK2 and NBN), as potential CRC susceptibility factors. Another aim of this study was to investigate expression profile of all human ABC transporter genes to follow their prognostic and predictive potential in colorectal carcinoma. Materials and methods: The polymorphisms and other...
Study of genetic factors modifying the risk of onset and progression of colorectal and pancreatic cancer
Mohelníková Duchoňová, Beatrice ; Souček, Pavel (advisor) ; Skálová, Lenka (referee) ; Macek, Milan (referee)
Introduction: The aim of this study was to evaluate the role of genetic and lifestyle factors in the risk of onset and progression of colorectal and pancreatic cancer. The first part deals with the etiological factors and the importance of polymorphisms in biotransformation enzymes and genetic alterations in the gene CHEK2 in the origin of these malignancies. In the second part, the ABC transporter genes were analyzed as potential prognostic and predictive markers of a treatment's outcome. Materials and methods: The polymorphisms and other genetic alterations were detected using real-time PCR, allelespecific PCR and PCR-RFLP methods in DNA which was extracted from the blood of patients. The frequency of polymorphisms was evaluated and their importance was assessed with regard to the available epidemiological data. Gene expressions were determined by qPCR in paired samples of tumor tissue and adjacent non-tumorous parenchyma. Results: A majority of the observed polymorphisms failed to show a relationship between their presence and the risk of any of these malignancies. CYP2A13 variant allele*7 coding inactive enzyme was found in 7 of 265 controls and in none of 235 pancreatic carcinoma patients. In contrast, GSTP1-codon 105 Val variant allele and GSTT1-null genotype were associated with an elevated...
Biotransformation of phenols by enzymatic systems of Candida tropicalis yeast and Comamonas testosteroni bacteria
Vilímková, Lenka ; Stiborová, Marie (advisor) ; Entlicher, Gustav (referee) ; Mareš, Jaroslav (referee)
Candida tropicalis yeast and bacteria Comamonas testosteroni have been considered to be able to metabolize phenol and utilize it as the only source of carbon and energy. In our laboratory we investigated the cytoplasmic enzymes responsible for the first and second step of phenol degradation, NADPH-dependent phenol hydroxylase of both C. tropicalis and C. testosteroni and catechol 1,2-dioxygenase of C. tropicalis. The aim of our study was to isolate and partially characterize those enzymes. Phenol hydroxylase purification consisted of preparation of cytosol from C. tropicalis yeast by fraction centrifugation, chromatography and re-chromatography on a column of DEAE Sepharose, fractionation by precipitation of the enzyme with polyethylene glycol 6000 and gel permeation chromatography on a column of Sephacryl S-300. Extracellular phenol hydroxylase of C. testosteroni was purified by fraction precipitation with polyethylene glycol 6000 and by gel permeation chromatography on 4B Sepharose and Sephacryl S-300. Catechol 1,2-dioxygenase was purified using the procedure consisting of: chromatography and re- chromatography on a column of DEAE Sepharose, lyophilization of the enzyme and gel permeation chromatography on a column of Sephadex G-100. The enzyme activity was determined by two methods: use of HPLC...

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