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Study on the induction of intestinal conjugation enzymes by food supplements
Hrdinová, Johana ; Hodek, Petr (advisor) ; Bárta, František (referee)
Cytochrome P450s (CYP) are enzymes, that play an important role in the metabolism of foreign compounds (e.g. drugs, carcinogens, pollutants) and they also participate in the metabolism of hydrophobic endogenic substrates (e.g. sterols, fatty acids, prostaglandins). Cytochromes of subfamily CYP1A are involved in activation of precarcinogens. Whereas the consumption of dietary supplements containing chemopreventive substances (e.g. flavonoids) that can prevent the process of carcinogenesis is significantly increasing in recent years, although these substances may also have a negative effect on the organism. That because these substances can induce the cytochrome P450s and thus increase the risk of activation precarcinogens. In this study had been investigated the inductive effect of some flavonoids compounds - β-naphthoflavone, myricetin, dihydromyricetin and a drug containing an extract of red vine leafs - Antistax®.
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Study on the interaction of chemopreventive compounds and food born carcinogens with cytochrome P450 enzymes
Brabencová, Eliška ; Hodek, Petr (advisor) ; Koblihová, Jitka (referee)
The use of food supplements containing natural chemopreventive compounds increased in recent years. Some of the most popular chemopreventive compounds are flavonoids. Due to their natural origin, flavonoids are generally accepted as safe compounds. They exert antioxidant, anti-cancer and anti-inflammatory properties. However, flavonoids should be considered as foreign compounds (xenobiotics). Flavonoids interact with many enzymes, among the most important belong cytochromes P450 (CYPs), key enzymes of the first phase of biotransformation of xenobiotics (e.g. drugs, carcinogens). CYPs catalyze reactions leading mainly to detoxification of xenobiotics. However, some CYPs are involved in the activation of carcinogens, particularly CYP1A1 and CYP1A2 activate e.g. heterocyclic amines. Flavonoids might enhance the activation of carcinogens via induction of these CYPs or stimulation of their activities and hence, increase the risk of a cancer development. The thesis is focused on the influence of flavonoids and food carcinogens on the induction and activity of CYP1A1 and CYP1A2 in liver and small intestine of rats. For the purpose of this study, the small intestine was dissected into three parts: proximal (nearest to stomach), middle and distal. Western blotting was used for the evaluation of CYP...
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Role of chemopreventive compounds and food additives in the process of metabolism and activation of carcinogens by cytochromes P450
Fousová, Petra ; Hodek, Petr (advisor) ; Hansíková, Hana (referee)
The origin of malignant tumors have different internal and external factors and also have been shown that, for majority of exogenous chemical carcinogens, the genotoxicity depends on metabolic activation through enzymes. Members of the subfamilies CYP1A are involved in activation of precarcinogens, for example the heterocyclic amine PhIP. One of the main approaches to achieve a reduction in a cancer risk is prevention. Recently, the consumption of dietary supplements containing various chemopreventive substances, such as flavonoids, has expanded. On the other hand, some negative effects of these compounds were also confirmed, especially their ability to induce cytochrome P450 and thus increase the risk of activating precarcinogens. In this study, the inductive effect of a single administration of chemopreventive compounds, namely the effect of -naphtoflavon to cytochrome P450, had been investigated. Furthermore, a sequential study was carried out. In this study rats were first given an inducer, the -naphtoflavon, and after a passed interval they were given the carcinogen PhIP. Finally, the effect of PhIP on the activity of cytochrome P450 has been studied in vitro. KEY WORDS: cytochrome P450, carcinogens, chemopreventive compounds
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Effect of chosen substances in food of animal origin in development of lifestyle diseases
ZÁHORKOVÁ, Jana
This bachelor thesis is devoted to the effect of harmful substances found in animal foods that affect the development of civilization diseases. Fish can contain carcinogenic substances, such as polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), pesticides, methylmercury and lead. Higher consumption of red meat and meat products increases the risk of cancer. It can be caused by heme content or substances given into the food during heat treatment or preservative treatment of meat. These compounds include heterocyclic amines (HCA), polycyclic aromatic hydrocarbons (PAHs), N-nitrosocompounds (NOC), nitrates and nitrites. High intake of fat containing saturated fatty acids (SFA) and trans-unsaturated fatty acids (TFA), increases the risk of obesity, cardiovascular diseases, diabetes mellitus and cancer.
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