|
|
Interaction of selected flavonoids with cytochromes P450 2B
Boštíková, Zdislava ; Hodek, Petr (advisor) ; Kubíčková, Božena (referee)
In recent years, there has been increased emphasis on healthy lifestyle, which includes, among others, consumption of natural nutrients in a form of various food supplements. These compounds, usually of a flavonoid character, show different chemopreventive effects such as anti-oxidant or anti-carcinogenic. The excessive consumption of these compounds can also have a negative impact on human health. Flavonoids may for instance influence the content of biotransformation enzymes, cytochromes P450, in the cells and thus influence the metabolism of foreign compounds. Such an influence might, as a result, lead to a development of carcinogenesis or inefficacy of certain medications. The main focus of this bachelor thesis is to study capabilities of two flavonoid compounds (myricetin and dihydromyricetin) to induce and inhibit cytochromes P450 of 2B family. By the Western blot method it was found that neither of the investigated flavonoids increased expression of CYP2B1/2 in livers, myricetin, or in any part of small intestine. In the case of dihydromyricetin there was noticed an induction of cytochromes P450 2B in the middle part of small intestine. The inhibitory potency of flavonoids was examined in vitro as an inhibition of 7-pentoxyresorufin O-depentylation catalyzed by CYP2B. Values of IC50 8,8μM and...
|
|
|
Inhibitors of tyrosine kinases as anticancer drugs of a new generation
Hromek, Vlastimil ; Stiborová, Marie (advisor) ; Bárta, František (referee)
At the present time many types of treatment are used for curing of different cancer diseases. Among the most common types of such treatment belong a surgery, radiotherapy, chemotherapy, and immunotherapy. In the case of chemotherapy, there is used a wide (broad) spectrum of chemotherapeutics such as alkylating agents, platinum compounds, antimetabolites, anthracyclines and, at the present time, also inhibitors of tyrosine kinases. The bachelor thesis describes different types of tyrosine kinase inhibitors and their use in treatment of several cancers. They become popular because of their high specifity and minimal side efects. The first successful use of a tyrosine kinase inhibitor was treatment of the patients suffering from chronic myelogenous leukemia (CML) with imatinib. Vandetanib is another inhibitor of tyrosine kinases that is now used for treatment of another cancer, the medullary thyroid cancer. During treatment, vandetanib is biotransformed with cytochromes P450, which are the terminal oxidases of a mixed function oxidase (MFO) system, into the less efficient metabolites. In the practical part of the bachelor thesis we isolated enzymes, which metabolize xenobiotics, including vandetanib. Rat liver tissue was used for isolation of NADPH:cytochrome P450 reductase, which was isolated as a...
|
|
|
Study of modified amino acid incorporation into cytochrome b5
Koberová, Monika ; Hodek, Petr (advisor) ; Pavlásková, Kateřina (referee)
A cytochrome b5 (cyt b5) can influence cytochrome P450 (CYP)-dependent reactions. In consequence of these reactions cytochrome b5 can participate in substance activation (for example drugs, carcinogens) or it can influence proportions of formed metabolites. A mechanism of cyt b5 action has not been fully explained yet. Elucidation of protein-protein interactions in monooxygenase system could explain of the mechanism of cyt b5 action. To study these interactions by using cross-linking techniques is necessary to prepare photolabile cyt b5, which after photoactivation generated higly reactive intermediates which can create a complex with nearby components of the monoogynesase system. This thesis describes how was developed the method for the production of recombinant cyt b5 with modified amino acids. Cyt b5 was expressed in a bacterial strain E. coli BL-21 (DE3) Gold. Before the expression induction, cells were transformed into the limiting medium (DMEM-LM) which did not contain L-leucine and L-methionine. The limiting medium was supplemented by deuterated amino acid d3-methyl-L-methionine and D,L-Leucine. Expressed cyt b5 was isolated and incorporation of d3-methyl-L-methionene has been verified by mass spectrometry. Cyt b5 was obtained mainly as the apoprotein (apo-cyt b5). That is why in this...
|
|
|
Účinky xenobiotik na oxidační stres, metabolizmus lipidů, integritu DNA a životaschopnost lidských buněk a rybích spermií in vitro
LINHARTOVÁ, Pavla
Pollution of the aquatic environment by inorganic and organic chemicals is a major factor posing a serious threat to the survival of aquatic organisms including fish. In addition balancing risks and benefits of fish consumption is nowadays an intensively discussed public health topic. Spermatozoa of almost all fish species are released into water environment where they can be directly exposed to various compounds, such as xenobiotics including toxic metals, prior to fertilization. In addition, exposure of parental adults to various xenobiotics may affect gamete quality, which may subsequently reduce fertilization success. On the other hand the advantages of eating fish are well-known, not only in the point that fish is a healthy source of protein and other nutrients, but eating contaminated fish may also confer various health benefits. Research over the past few decades has shown that the nutrients and particularly the n-3 fatty acids (FA) found in fish and seafood, are for examples protective against cardiac diseases and have a positive impact on brain development. The thesis provides a focus on two different cell model types. Firstly, human hepatocellular cells (Hep G2, ATCC) were used as in vitro tool for studying the effect of the intake of cadmium (Cd2+) contaminated fish on cytotoxicity, oxidative stress and fatty acid and phospholipid class compositions. Secondly, spermatozoa of one threatened species of fish, sterlet (Acipenser ruthenus) were used as in vitro model for studying effect of potentially hazardous xenobiotic compounds' occurring in open waters. Sperm from sterlet were exposed for 2h to environmentally relevant concentrations of DQ (0-150
|
|
|
Use of oxidation processes (AOP) for removal of micropolutants
Stříteský, Luboš ; Pešoutová,, Radka (referee) ; Hlavínek, Petr (advisor)
This thesis deals with advanced oxidation processes (AOPs) and it’s use for removal of micropollutants from wastewater. The first chapter explains the need AOPs, water quality, pollution and substances that are present in the water. Further, the first chapter outlines approach of the current legislation to micropollutants. The second chapter explains the theory and principle of operation of AOPs. This chapter is divided into two sections. The first section describes AOPs, which were tested at selected WWTP. In the second section, there are described some other AOPs. The third chapter is a literature retrieval of AOPs dealing with the removal of micropollutants. This chapter is focused on the removal of hormones by AOPs using ozone-based AOPs. The fourth chapter describes the actual testing of selected AOPs. The chapter describes selected WWTP, pilot-scale AOP unit and test results. In the last chapter there is designed and described full-scale AOP tertiary unit for removing of micropollutants. The last chapter also contains economic analysis of the proposed tertiary unit.
|
|
|
Selection of suitable bioindicators for the determination of xenobiotics residuals
Musil, Jan ; Vondráčková, Ilona (referee) ; Vávrová, Milada (advisor)
Bio-indicators are organisms, which we can use to evaluate contamination of terestrial and aquatic ecosystems by xenobiotics. This thesis deals above all with bio-indicators of vegetal and animal origin, which are capable to identify and quantify persistent organic pollutants and its residual contamination. This xenobiotics comes from human activities, most by consumer and automotive industry, inconsiderate agriculture. Thanks to its unpremeditated application and waste disposal, which are contaminated with them, ecosystems are infested and persistent organic pollutant‘s residuals are persisting for decades. By the help of bio-indicators we can find the source of contamination and size up its seriousness, we can observe its development and biological effect on organisms, which live in contaminated areas. In this thesis attention is given especially to polychlorinated bifenyls (PCB), polyaromatic hydrocarbons (PAH), organochlorinated pesticides (OPC). polybrominated difenylethers (PBDE) and PCCDs/Fs, its influence on the health and its distribution in our surroundings, especially in waste dumps and forgotten pollutants sources.
|
|
|
Efekt xenobiotik na DNA integritu a fyziologii rybích spermií
LINHARTOVÁ, Pavla
Pollution of the aquatic environment with xenobiotics has become a serious health concern in recent years. In the present study the effect of DQ, TBBPA, BPA and VIN on sperm quality parameters, DNA integrity and oxidative stress indices in sterlet (Acipenser ruthenus) sperm and sperm from brook trout (Salvenilus fontinalis) were investigated. To do this, an in vitro spermatozoa motility assay was used by a computer-aided Motion-Analysis system. The sperm of sterlet (Acipenser ruthenus) was diluted to obtain the spermatozoa density of 5×108 cells×ml?1 and then exposed for 2 h to final concentrations of xenobiotics: DQ - 25, 50, 100 and 150 ?M, TBBPA - 0.5, 1.75, 2.5, 5, 7.5 and 10 ?g/l, BPA - 0.5, 1.75, 2.5, 5 and 10 ?g/l and Vin - 0.5, 1.75, 2.5, 5 and 10 ?g/l. Spermatozoa velocity and percentage of motile sperm were significantly decreased at each time post-activation compare to control. The level of DNA damage expressed as a % DNA in Tail and Olive Tail moment significantly increased when spermatozoa were exposed to higher concentrations of xenobiotics. The level of oxidative stress indices lipid peroxidation (LPO) and carbonyl derivatives of proteins (CP) and antioxidant activity of superoxide dismutase (SOD) increased significantly with increasing concentration of xenobiotics. On the other hand the intracellular ATP content in sperm samples had a significantly decreasing effect. In short, xenobiotics can induce reactive oxygen species (ROS) stress in fish spermatozoa, which could impair the sperm DNA integrity, quality and antioxidant defense system. The present study confirms that environmental concentrations of xenobiotics are capable to induce oxidative stress, leading to impaired sperm quality, DNA fragmentation and intracellular ATP content Obtained results also suggested that the use of fish spermatozoa in vitro assays may provide a novel and efficiently means for monitoring residual pharmaceutical in aquatic environment.
|
|
| |
|
| |
|
| |
guest ::
