Inhibition of ethoxyresorufin deethylase activity by natural flavonoids in human and rat liver microsomes

Abstract
Several flavones and flavonols (chrysin, quercetin, luteolin, flavone and 7, 8‐benzoflavone) were found to inhibit ethoxyresorufin deethylase (EROD) activity in human and rat liver microsomes. In man, molecules without hydroxyl groups are more powerful inhibitors than polyhydroxylated flavonoids (7, 8‐benzoflavone > flavone > chrysin > luteolin > quercetin > morin). In rat, chrysin was the strongest inhibitor and the less effective were morin and 7,8‐benzoflavone. For all molecules human microsomes were more sensitive than rat microsomes. The most important difference concerned 7,8‐benzoflavone which was 10 000‐fold more potent in man.