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Modulation of biotransformation and antioxidant enzymes by selected natural compounds
Lněničková, Kateřina ; Szotáková, Barbora (advisor) ; Anzenbacherová, Eva (referee) ; Trejtnar, František (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Biochemical Sciences Candidate: Mgr. Kateřina LNĚNIČKOVÁ Supervisor: prof. Ing. Barbora SZOTÁKOVÁ, Ph.D. Title of Doctoral Thesis: MODULATION OF BIOTRANSFORMATION AND ANTIOXIDANT ENZYMES BY SELECTED NATURAL COMPOUNDS Public interest in various dietary supplements containing herbs, herbal extracts or isolated active compounds has increased significantly over past decades. Consumption of these supplements increases worldwide and they are often consumed in unreasonably high doses, as they are generally considered as safe. Upon the intake to organism, these compounds are, as other xenobiotics, modified mostly by xenobiotic-metabolizing enzymes and they could influence these enzymes at the same time. Potential modulation of xenobiotic-metabolizing enzymes' activity (induction or inhibition) can seriously affect pharmacokinetics of concomitantly administered drugs. Knowledge of the possible impact of natural compounds on the xenobiotic-metabolizing enzymes is essential for their safe use. The aim of this doctoral thesis was to study the effects of selected herbal extracts and their active chemical constituents on the activity and expression of xenobiotic-metabolizing and antioxidant enzymes. We have focused on the study of effects of...
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Effect of colchicine on P-glycoprotein expression and activity in caco-2 cells
Houdková, Tereza ; Pourová, Jana (advisor) ; Trejtnar, František (referee)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Pharmacology and Toxicology Candidate: Tereza Houdková Supervisor: PharmDr. Jana Pourová, Ph.D. Title of diploma thesis: Effect of colchicine on P-glycoprotein expression and activity in caco-2 cells The caco-2 cell line is one of the most widely used human cell culture models. These cells derived from human colorectal adenocarcinoma and have been accepted as a reliable in vitro model for intestinal drug excretion mediated by P-glycoprotein studies. P-glycoprotein is an ATP-dependent efflux pump encoded by the MDR1 gene in humans, which is highly expressed in several cancer cells conferring a multidrug resistance phenotype. P-glycoprotein is inducible by many drugs including dexamethasone, rifampicin, the herbal antidepressant St. John's wort (hyperforin and hypericin) and chemotherapeutic agents, namely doxorubicin, daunorubicin and vinblastine. The sensibility of P- glycoprotein from caco-2 cells to different inducing compounds is yet to be clearly established. Colchicine is a toxic natural product and secondary metabolite, originally extracted from plants of the genus Colchicum - Colchicum autumnale. This compound is used as an anticancer drug and was already reported as a P-glycoprotein inducer. Thus, the main...
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Changes in expression of biotransformation enzymes in nematodes affected by albendazole
Štěrbová, Karolína ; Skálová, Lenka (advisor) ; Trejtnar, František (referee)
5 ABSTRACT Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Biochemical Sciences Candidate: Bc. Karolína Štěrbová Supervisor: prof. RNDr. Lenka Skálová Ph.D. Title of diploma thesis: Changes in expression of biotransformation enzymes in nematodes affected by albendazole Barber's pole worm (Haemonchus contortus) is highly pathogenic parasitic nematode, which assaults gastrointestinal system of small ruminants. Disease. Which caused is named by the agent haemonchoses. Long-term infection leads to develop of anaemia, lose weight of host and often even death. For treatment of this disease, synthetic antiparasitic drugs called anthelmintics are used. However, worldwide problem is growth of resistance against all used anthelmintics. Cause of this problem is probably common and unreasonable using of anthelmintics and the exposure of the parasites to sub-lethal doses. This thesis is focused on study of the mechanisms of resistance of barber's pole worm to albendazole, anthelmintic belonging to benzimidazoles group. The increased expression of biotransformation enzymes could contribute to resistance development. In our study, the influence of albendazole on expression of selected genes in adults of H. contortus from the ISE (Inbread Susceptible Edinburgh) strain was studied. Worms...
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Study of transport mechanisms of xenobiotics
Richtrová, Monika ; Trejtnar, František (advisor) ; Melicharová, Ludmila (referee)
Aim: Graduation theses was aimed on the use of the isolated rat renal cells to study of transport mechanisms of the selected receptor - specific peptides from the group of somatostatin analogues labeled with convenient radionuclides - 111In-DOTA-octreotate, 125IDOTA- octreotate. Experiment with the selected model substances - sucrose and α-methyl glucoside as markers of active and passive transport was executed. Accumulation process of α-methyl glucoside was tested in renal and pancreatic cells. Further, accumulation of the radiopeptides was researched in presence of the potential inhibitors, which could reduce to retention these radiopeptides and thus also clinically undesirable renal radiotoxic insult. Methods: Isolated rat renal cells were prepared by collagenase technique. Pancreatic rat exocrine cells were prepared from cell line tumor cells. Viability of cells was tested with trypane blue. The accumulation rate of model substances was compared with the accumulation radiopeptides rate: 111In-DOTA-octreotate, 125I-DOTA-octreotate. Transport character was also monitored for low temperatures. Megalin/cubilin membran transport system was researched via their ligands (e.g. albumin, gentamicin), which could inhibit accumulation of the radiopeptides by competition in transport. Results: Cells...
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Permeation studies of a set antihistaminic drugs and the influence of verapamil in an in vitro Blood-brain barrier model
Mandíková, Jana ; Šimůnek, Tomáš (advisor) ; Trejtnar, František (referee)
Studies of drug permeation across the blood-brain barrier (BBB) are an indispensable part of the drug development strategy. Recent in vitro studies have suggested that P-gP and passive membrane permeability may influence the brain concentrations of non-sedating (second generation) H1-antagonists. The purpose of this thesis was to determine the importance of P-gP mediated efflux of the first and the second generation of H1-antagonists in an in vitro BBB model and the influence of P-gP inhibitor verapamil. CNS adverse effects of the first generation of H1-antagonists are linked with their ability to penetrate the BBB and cause sedation and drowsiness. The second and the third generation of H1-antagonists are relatively free of sedation and their limited brain penetration has been suggested to arise from P-gP mediated effux (Obradovic, Dobson et al. 2006). In our in vitro PBMEC/C1-2 model, three H1-antagonists (promethazine, fexofenadine and cetirizine) and a known P-gP substrate rhodamine 123 were tested for their permeation properties. Firstly, P-gP experiments in PBMEC/C1-2 was proven by western blotting. The functional activity of P-gP was assessed by the permeation experiments with an established Transwell in vitro model. The resulting drug quantificantion were evaluated by RP-HPLC and fluorescence...
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Interspecies comparison of plasma protein binding of two radiolabelled complexes
Smolová, Lenka ; Lázníček, Milan (advisor) ; Trejtnar, František (referee)
This paper engages in the newly prepared bifunctional chelate DTPA-oxn which has a potential use in radiolabelling biological macromolecules. The aim of the paper was to prepare a radiolabelled bifunctional chelate DTPA-oxn with a suitable radionuclide, the 90Y has been used. Binding of 90Y-DTPA-oxn to human, bovine, rabbit and rat plasma protein was determined. An equilibrium dialysis at 37řC was employed for the plasma protein binding determination. The received results received were compared with the results of plasma protein binding of a clinically routinely used bifunctional chelate DTPA radiolabelled with 99mTc (99mTc-DTPA). The results showed a low plasma protein binding of these radiolabelled chelates. Interspeices comparison demonstrated that the results obtained for human, bovine and rat plasma are comparable, whereas those obtained for rabbit plasma are higher. This brings a conclusion that the binding of 90Y-DTPA- oxn and 99mTc-DTPA to plasma protein is not a factor that can influence their biological behavior.
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The pharmacotherapy of dyslipidemia
Řeháčková, Renata ; Melicharová, Ludmila (advisor) ; Trejtnar, František (referee)
Dyslipidemia (DLP) represents one of the most significant risk factors of atherosclerosis. Results of many clinical studies proved that effective treatment of dyslipidemia markedly decreases cardiovascular risk. Hypolipidemic treatment becomes one of the most effective treatment options (modalities) in prevention of CHD (coronary heart disease) and other cardiovascular diseases. Basic approach of the DLP treatment is nonpharmacologic therapy, e.g. change of life habits, stop of smoking, change of dietary habits, regular exercise, reduction of abnormal weight. In primary prevention settings the pharmacotherapy should commence after the failure of 3 to 6 months nonpharmacologic measures. In secondary prevention in patients with CHD it is recomended to start DLP treatment immediately, at the latest on release from the hospital. The care for the patient with hyperlipoproteinemia is comprehensive and should include rational control of diabetes, hypertension, obesity, adequate treatment of CHD and complications of atherosclerosis. The statins are the choice of medication in isolated hyperlipoproteinemia. If the target values are not reached by monotherapy, combination therapy by statin end ezetimib may be tried. The choice of lipid lowering drug should be decided on the major metabolic abnormality. When...
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Study on renal transport of radiopharmaceuticals
Kaňoková, Jana ; Trejtnar, František (advisor) ; Pávek, Petr (referee)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Jana Kaňoková Supervisor: Doc. PharmDr. František Trejtnar, CSc. Title of diploma thesis: Study on renal transport of radiopharmaceuticals Radiolabelled receptor-specific peptides from the group of gastrin and bombesin derivatives are currently intensively researched substances in terms of targeting certain tumors. The main limit in their application is the intense renal accumulation and subsequent radiotoxicity. The aim of this experimental study was to determine and then compare the renal uptake of DOTA-bombesin and one of the gastrin derivatives - DOTA-sargastrin labeled with indium-111 and lutetium-177. Moreover, the other goal of this study was to assess the potential role of megalin system in the active endocytosis in the renal accumulation of these substances. Isolated rat kidney cells obtained by the collagenase perfusion method were used as an experimental model. The uptake of studied radiopeptides was further compared with the degree of accumulation of selected comparators with different renal accumulation (99m Tc- DTPA, 99m Tc-MAG3). The results of accumulation studies showed that the accumulation of the labeled derivatives of DOTA-sargastrin in rat kidney cells was...
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Modulatory effects of quercetin and rutin on cytochrome P4501A expression and activity in intestinal cells
Volková, Marie ; Skálová, Lenka (advisor) ; Trejtnar, František (referee)
Charles University in Prague Faculty of Pharmacy in Hradec Králové Department of Biochemical Sciences Candidate: Marie Volková Supervisor: Doc. RNDr. Lenka Skálová, Ph.D. Title of diploma thesis: Modulatory effects of Quercetin and Rutin on the activity and expression of cytochrome P4501A in the intestinal cells Flavonoids originate as the secondary metabolites of plants and they are daily consumed in fruits and vegetables. They show the antioxidant, antiinflammatory, anticarcinogenic and other healthy effects. A potential anticarcinogenic effect is mediated by the strong antioxidant activity, but it can also include an inhibition of xenobiotica - metabolizing enzymes to the carcinogenic compounds. This work has examined the potential inhibition effect of the flavonoids Rutin and Quercetin on an activity and expression of cytochrome P4501A (CYP1A) in the intestinal cells. Quercetin is the most abundant flavonoid and Rutin is its most abundant glycosidic form. CYP1A is responsible for an activation of many pre - carcinogenic ingested substances. The study was conducted on the intestinal cell line HCT-8. CYP1A's enzymatic activity was measured by EROD/MROD activity; quantity of CYP1A's protein was set by Western blotting. Quercetin at the concentration of 1 µM caused slightly increased EROD/MROD...
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