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Interaction of selected flavonoids with N-acetyltransferases
Veselá, Šárka ; Hodek, Petr (advisor) ; Bořek Dohalská, Lucie (referee)
Flavonoids are natural compounds synthesized in plants as secondary metabolites. Due to broad range of their biological effects, for example we can mention antioxidant, hepatoprotective or antibacterial effects, flavonoids are increasingly used as a component in dietary supplements. Besides positive effects, some negative effects were observed, especially mutagenic and pro-oxidative properities. The biotransformation is an important process which is affected by flavonoids. Interactions between flavonoids and biotransformation enzymes in both phases of biotransformation are essential for the metabolism of drugs and carcinogenesis processes. In this bachelor thesis the influence of selected flavonoid compounds, myricetin and dihydromyricetin, on the activity of N-acetyltransferase 1 and 2, enzymes of second phase of biotransformation, was studied. Mainly the mechanism of this influence was tested. The inhibition of human recombinant and of N-acetyltransferase 1 and 2 by myricetin and dihydromyricetin was proved. The more in-depth study of interactions of N-acetyltransferase 1 and 2 with selected flavonoids shows that raising concentration of second substrate (p-aminobenzoic acid, sulfamethazine) does not lead to reduction of inhibition effect. Thus, it is highly probable that both flavonoids already...
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The Study of metabolism of dihydromyricetin
Blecha, Tomáš ; Moserová, Michaela (advisor) ; Koblihová, Jitka (referee)
More attention has recently been paid to the chemopreventive compounds contained in food of plant origin. A large group of chemopreventive compounds are represented by flavonoids contained in many dietary supplements. One of the representatives of this group is dihydromyricetin, which is attributed to positive impact on human organism, in particular by its antioxidant, anti-inflammatory and hepatoprotective effects. Some flavonoids can act as modulators of enzymes of phase I and phase II metabolism of xenobiotics biotransformation by their inhibition or induction which can causean interference with endogenous metabolism. In first part of this present work, the effect of selected flavonoid compounds, such as biochanin A, dihydromyricetin, myricetin and their combinations on the gene expression of cytochrome P450 2E1 (CYP2E1) and sulfotransferases 1A1 (SULT1A1) in liver and small intestine of laboratory rats was studied. The small intestine was divided into three parts namely a proximal, middle and distal. At first, isolation of total RNA was made followed by conversion into cDNA using random hexamers as primers. By real-time PCR a significant decrease in gene expression of both enzymes in liver was found. The highest induction of gene expression was observed for both enzymes in proximal part of...
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Study of effect of dihydromyricetine on cytochrome P450 1A1 expression in organs of the rat
Feriančiková, Barbara ; Moserová, Michaela (advisor) ; Dračínská, Helena (referee)
Polyphenols are one of the largest groups of substances in the plant kingdom. They are widely represented in fruits, vegetables and many beverages. They are included up to 80% of higher plants. Moreover, there is an increasing interest to know of their metabolism. Polyphenols are considered as substances with generally positive effects. However, it is necessary to look at them as xenobiotics. However, it is necessary to regard these compounds as xenobiotics. Polyphenols are able to interact with key phase I biotransformation enzymes such as cytochrome P450. In the present work we studied the influence of dihydromyricetine on induction of CYP1A1 in the body of the rat, particularly in the organs involved in the metabolism of xenobiotics, such as liver and small intestine. The small intestine was divided into three sections - a proximal, middle and distal. The evaluation was performed by real-time polymerase chain reaction. It was found dihydromyricetine did not significantly affect gene expression of CYP1A1 in liver. On the other hand, the change of gene expression on mRNA level was observed in small intestine; the significant increase was found in the proximal part, and small decrease in the middle part. Key words: dihydromyricetine, cytochrome P450 1A1, mRNA, RT-PCR
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