National Repository of Grey Literature 19 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
LC-MS/MS study of phase one in vitro biotransformation of potential drugs against Alzheimer's disease
Kuřátková, Aneta ; Kučera, Radim (advisor) ; Váňová, Nela (referee)
No treatment that would completely stop the progression of Alzheimer's disease has not been found yet. Recently used tacrine showed good results in the treatment of Alzheimer's disease, however long-term use led to chronic hepatotoxicity due to its metabolites. This master thesis deals with the compound 7-phenoxytacrine, one of the promising tacrine derivatives, which is one of the candidates for potential use in the therapy of Alzheimer's disease. Due to the formation of hepatotoxic metabolites of tacrine after the biotransformation in human liver, it appears necessary to identify the emerging metabolites of 7-phenoxytacrine molecule. Within this master's thesis in vitro biotransformation study of 7-phenoxytacrine using human liver microsomes was performed. High performance liquid chromatography with tandem mass spectrometry was used to determine the parent substance and the seventeen 7-phenoxytacrine metabolites. The analytical method showed the formation of six monohydroxylated and eleven dehydroxylated metabolites of 7-phenoxytacrine. Thus, we concluded that hydroxylation is the major metabolic reaction after in vitro microsomal biotransformation. In addition to the identification of metabolites, a quantification and microsomal stability study, including the determination of the amount of...
Application of LC-MS/MS methods to in vitro transport experiments
Salvová, Šárka ; Váňová, Nela (advisor) ; Kastner, Petr (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department: Deparrment of Pharmaceutical Chemistry and Pharmaceutical Analysis Candidate: Šárka Salvová Supervisor: PharmDr. Nela Váňová, Ph.D. Title of Thesis: Application of LC-MS/MS methods to in vitro transport experiments Gilteritinib, an antineoplastic drug, is used for targeted anticancer therapy. It belongs to the group of receptor tyrosine kinase inhibitors. Its structure is based on a pyrazinecarboxamide skeleton. So far, it has been chromatographically determined in biological material only from plasma. In this diploma thesis, gilteritinib was analyzed from Opti-MEM cell medium to be used in vitro transport experiments. Subsequently the LC-MS/MS method was optimized and validated. During progression and optimization of the LS-MS/MS method, the Thermo Finnigan LCQ Advantage Max Ion Trap was observed that with an increasing number of injections had been shown increasing signal suppression for gilteritinib and its internal standard (maraviroc), which reached up to 75 % after only 30 sprays. Contamination of the inlet to the ion transfer capillary, to which the ion source (electrospray) is placed diagonally, was also visible. Thereafter it was tested whether another construction of the ion source (orthogonal position of electrospray)...
Development and Validation of HPLC Method for Determination of 3-Hydroxykynurenine in Biological Material
Knoblochová, Dominika ; Kastner, Petr (advisor) ; Váňová, Nela (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Chemistry and Pharmaceutical Analysis Candidate: Dominika Knoblochová Supervisor: PharmDr. Petr Kastner, Ph.D. Title of thesis: Development and Validation of HPLC Method for Determination of 3-Hydroxykynurenine in Biological Material 3-Hydroxykynurenine is one of the metabolites of tryptophan and is studied especially for its oxidative modulatory activity, which provides the ability to protect cells from oxidative stress. It is formed from kynurenine by catalysis of the enzyme kynurenine monooxygenase, whose activity is monitored at the Department of Pharmacology and Toxicology. It is necessary to quantify 3-hydroxykynurenine in a biological matrix for its study. The aim of this diploma thesis was to develop an HPLC method for the determination of 3-hydroxykynurenine in biological material using high performance liquid chromatography and subsequent method validation. During development, several mobile phases with different pH values were tested. The resulting mobile phase consisted of 100 mM formic acid (pH = 2.25) and methanol (95:5). Different types of stationary phases were also tested, from which a YMC TRIART PFP column with dimensions of 15 × 3 mm and a particle size of 5 µm was finally chosen. A UV-VIS...
Optimization of derivatization reaction conditions for GC-MS analysis of selected compounds
Jan, Tomáš ; Kučera, Radim (advisor) ; Váňová, Nela (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Chemistry and Pharmaceutical Analysis Supervisor: doc. PharmDr. Radim Kučera, Ph.D. Candidate: Tomáš Jan Title of Thesis: Optimization of derivatization reaction conditions for GC-MS analysis of selected compounds Quinolinic acid is an endogenous molecule, downstream product of the kynurenine pathway, through which the amino acid L-tryptophane is metabolised. Quinolinic acid acts as an agonist at the NMDA receptor. Overactivity of this receptor leads to the cell death of neurons. Current research shows the connection between a high level of quinolinic acid and a higher risk of neurodegenerative diseases development and behavioural disorders. The level can be increased by the excessive intake of tryptophane (e.g. food supplements declaring calming effect and mental health support) or ongoing inflammation in the organism. The current work deals with the development of an analytical method for the determination of quinolinic acid in various biological matrices using GC/MS and complements methods analysing other metabolites of tryptophan. Derivatization by alkyl chloroformate was met with success. The selectivity was compared on column RTX-5MS containing non-polar stationary phase and polar column SLB-IL59 using ion...
HPLC determination of oxidative stress
Kalíšková, Tereza ; Váňová, Nela (advisor) ; Lochman, Lukáš (referee)
Reactive oxygen and nitrogen species have a physiological role in the organism, but their extensive production can damage cells and result in many diseases. By interaction of biomolecules with reactive oxygen and nitrogen species are biomolecules damaged. Damaged lipid, protein and DNA molecules then serve as biomarkers of oxidative stress and allow its evaluation. Oxidative stress can be caused by external factors such as drugs and then it may occur as adverse and toxic effects. It is important to monitor a drug's ability to induce oxidative stress to monitor drug safety. A high-performance liquid chromatography method coupled with tandem mass spectrometry has been developed to determine malondialdehyde from the cell pellet as a biomarker of lipoperoxidation. The greatest emphasis was given to the optimization of sample preparation by deproteination, derivatization and solid-phase extraction. The method was validated with acceptable specificity, accuracy, precision, recovery and matrix effect. The method complies with the requirements of the European Medicines Agency for the validation of bioanalytical methods. The method can determine intracellular malondialdehyde in the concentration range 0,1-2 μmol∙dm-3 . This method was successfully applied to the analysis of biological samples from in vitro...
Determination of oxidative stress biomarkers by HPLC
Váňová, Nela ; Jun, Daniel (advisor) ; Doležal, Rafael (referee) ; Hroch, Miloš (referee)
and keywords Although reactive oxygen and nitrogen species have a fundamental role in physiological processes occurring in living organisms, their overproduction induced by endogenous and/or exogenous sources may lead to serious imbalance in redox homeostasis, damage to intracellular components and thus, dramatically alter their function or even trigger cell death. Oxidative stress is believed to be very important mechanism of toxicity of xenobiotics, including drugs, and may be responsible for the development of their unwanted side effects. Considering a very low number of studies evaluating oxidative stress after the treatment with oxime reactivators of acetylcholinesterase (AChE) in vivo and in vitro, the relationship between their toxicity and generation of specific biomarkers of oxidative damage is not still fully understood. In order to monitor antioxidant/prooxidant properties of drugs, high performance liquid chromatography method coupled with tandem mass spectrometry (LC-MS/MS) for simultaneous determination of two biomarkers of oxidative stress, malondialdehyde (MDA) and 3-nitrotyrosine (3-NT), in biological matrices was developed. Validation of this LC-MS/MS method demonstrated the acceptable appreciable selectivity, accuracy, intra- and interday precission, and recovery of sample...
Analysis of oxidative and free radical induced DNA damage
Váňová, Nela ; Kučera, Radim (advisor) ; Kovaříková, Petra (referee)
Analysis of oxidative and free radical induced DNA damage Diploma thesis Nela Váňová Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Chemistry and Pharmaceutical Analysis Free radicals and reactive oxygen species (ROS) are highly reactive molecules capable of modifications of biomolecules, including DNA. 5',8-cyclopurine-2'deoxynucleosides represent a group of DNA lesions characterized by concomitant damage to both sugar and base moieties of the same purine nucleoside that are together with 8-oxo-2'-deoxypurines among the major lesions formed by attack of free radicals (e.g. hydroxyl radical). Quantification of oxidative and free radical induced DNA lesions as biomarkers of oxidative stress has a high importance in study of their role in human health and disease. For quantification of these DNA lesions in gamma irradiated samples, high performance liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) will be utilized. Before injection into the LC/MS/MS, irradiated samples, treated by enzymatic digestion in order to gain free nucleosides, have to be desalted and DNA lesions have to be separated from undamaged nucleosides. A new HPLC/UV method was developed for separation of (5'R)-5',8-cyclo-2'- deoxyadenosine;...
UHPLC-MS/MS analysis of selected drugs in a biological material
Motyčka, Filip ; Štěrbová, Petra (advisor) ; Váňová, Nela (referee)
Dexrazoxane (DEX), a bisdioxopiperazine derivative, is the only clinically used drug effective against anthracycline-induced cardiotoxicity. First studies indicated that DEX is a pro-drug bioactivated in cardiomyocytes by enzymatic hydrolysis of piperazine rings to its active metabolite - ADR-925. However, further research revealed that effective cardioprotection induced by bisdioxopiperazine compounds is more likely related to topoisomerase IIβ depletion induced by DEX itself. The only bioanalytical method for simultaneous determination of DEX and its metabolite was developed using HPLC-MS/MS system. Nevertheless, the analysis requires 30 min for each run, which does not accomplish requirements for modern bioanalysis. The aim of this project is to develop and validate a fast UHPLC-MS/MS method for determination of DEX and ADR-925 in plasma. The analyses were performed using an UHPLC system coupled to triple quadrupole mass spectrometer with ESI source in positive ion mode (both Shimadzu). Following stationary phases were tested: ZORBAX Bonus-RP (100 mm × 3.0 mm, 1.8 μm), Luna Omega Polar C18 (100 mm × 2.1 mm, 1.6 μm) and Kinetex F5 column (100 mm × 2.1 mm, 1.7 μm). Mixtures of acetonitrile or methanol with different concentrations of ammonium formate or formic acid were tested as mobile phase with...
The influence of solubility and adsorption on plastic materials on transport experiments
Šilhanová, Marie ; Kučera, Radim (advisor) ; Váňová, Nela (referee)
Charles University Faculty of Pharmacy in Hradec Králové Department: Department of Pharmaceutical Chemistry and Pharmaceutical Analysis Student: Marie Šilhanová Supervisor: doc. PharmDr. Radim Kučera, Ph.D. Title of diploma thesis: The influence of solubility and adsorption on plastic materials on transport experiments From transport experiments on cell culture models we get valuable information about transport mechanism of drugs in organism. In vitro experiments are conducted for example on Transwell type inserts. During the experiment it was discovered that the results are not homogeneous, and the quantity of a substance in the solution decreases apparently, the reason behind this is inadequate solubility of lipophilic substances or their adsorption on the surface of plastic materials used in the experiment. Due to these problems we experience significant bias. This thesis is focused on antivirotics that did not perform well during transport experiments. First, HPLC/MS methods were developed, and they were used for concentration measurement of samples containing individual antivirotics. The drugs were tested under wide range of conditions so possible changes in effects of adsorption on plastic surfaces and solubility of drugs could be observed. The substances were divided into groups based on...
Optimization of metabolomic workflow for a comparison of impurity profiles of levothyroxin tablets using UHPLC-HRMS
Hrušková, Anna ; Nováková, Lucie (advisor) ; Váňová, Nela (referee)
Charles University, Faculty of Pharmacy in Hradec Králové Department of Analytical Chemistry Candidate: Bc. Anna Hrušková Supervisor: prof. PharmDr. Lucie Nováková, Ph.D. Title of Diploma Thesis: Optimization of metabolomic workflow for a comparison of impurity profiles of levothyroxin tablets using UHPLC-HRMS The aim of this diploma thesis was to compare 3 designs of measuring the impurity profiles of levothyroxine tablets and to evaluate the most suitable procedure. Analyses were performed by ultra-high performance liquid chromatography coupled with high resolution mass spectrometry. Levothyroxine drug products are used to supplement reduced thyroid function. In this work, 23 batches of tablets from 2 different manufacturers were analysed. The optimization of the tablet sample and internal standard preparation method and the compilation of 3 measurement designs using data from the preliminary screening was the first step. The designs were compiled as targeted metabolomics analyses. Then, a targeted analysis of 4 known impurities in designs 1 and 2 was performed, which was semi-quantitative (relative content of impurity to levothyroxine content). Differences in impurity content between designs were also evaluated. The next step was to compare individual designs in terms of variability, which was...

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2 VAŇOVÁ, Naďa
1 Váňová, Nicol
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