Metabolism of flavonoids mediated by cytochrome P450 3A4

Flavonoidi su fenolni spojevi koje sintetiziraju biljke te se kao takvi pojavljuju u većini jestivog voća i povrća. Uobičajeni ugljikov skelet C6-C3-C6 čini njihovu temeljnu strukturu, a razlikuju se po vrsti i poloţaju supstituenta. Generalno su prihvaćeni kao supstancije koje promoviraju zdravlje zbog svojeg antioksidativnog, antikancerogenog, antivirusnog, protuupalnog učinka, ali se zna da ovisno o dozi mogu djelovati i proupalno, prooksidativno i drugo. Kao i drugi ksenobiotici, i flavonoidi u organizmu podlijeţu apsorpciji, raspodjeli, metabolizmu i eliminaciji. U ovom radu od posebnog je interesa metabolizam aglikona flavonoida posredovan citokromom P450 3A4. Za potrebe ovoga rada ispitano je jedanaest flavonoida koji su prethodnim probiranjem na humanim jetrenim mikrosomima pokazali metabolizam posredovan citokromima P450. Za identifikaciju metabolita pojedinih flavonoida primijenjena je tekućinska kromatografija spregnuta sa spektrometrijom masa (LC-MS) i UV-Vis detektorom. Proučavajući UV kromatograme, kromatograme izdvojenog iona, vremena zadrţavanja spojeva i dobivene molekulske formule, moţemo zaključiti o prisutnosti metabolita i tako potvrditi reakcije biotransformacije posredovane citokromom P450 3A4 za pojedini flavonoid. Od ispitanih flavonoida tri su pokazala da je u njihov metabolizam uključen CYP3A4 enzim: 7-hidroksiflavon, za koji su potvrđena dva hidroksilirana metabolita, sakuranetin, za koji je potvrđen jedan hidroksilirani metabolit te tangeretin za koji su potvrđeni hidroksilirani metabolit te jedan koji je metiliran na dvije pozicije. Za flavonoide čije smo metabolite detektirali postoji potencijal interakcija s lijekovima koji se metaboliziraju posredstvom citokroma P450 3A4.Flavonoids are phenolic compounds synthesized by plants and as such appear in most edible fruits and vegetables. Thez are characterized by carbon skeleton C6-C3-C6, and differ by the type and position of the substituent. They are generally accepted as substances that promote health due to their antioxidant, anticancer, antiviral, anti-inflammatory effect, but depending of the dose they may be pro-inflammatory, proxidative, etc. Like other xenobiotics, flavonoids in the body are subject to absorption, distribution, metabolism and elimination. In this study, the metabolism of aglycone of flavonoids mediated by cytochrome P450 3A4 was of particular interest. For the purpose of this study, eleven flavonoids were tested, thosethat were metabolised by cytochrome P450 in the previous screening performed on human liver microsomes. Liquid chromatography coupled with mass spectrometry (LC-MS) and UV-Vis detector was used to identify the metabolites of specific flavonoids. By studying UV chromatographs, isolated ion chromatography, time retention and the resulting molecular formula, we can conclude the presence of the metabolite and thus confirm the P450 3A4 mediated biotransformation reactions for each flavonoid. Of the tested flavonoids, three showed that their metabolism included CYP3A4 enzyme: 7-hydroxyphlavone, for which two hydroxylated metabolites were confirmed, sakuranetin, for which a hydroxylated metabolite and a tangerine for which a hydroxylated metabolite was confirmed and one didemethylated product. For these flavonoids there is potential for interaction with drugs metabolised by the same cytochrome P450 3A4