The activity of liver oxidative enzymes after single and multiple grapefruit juice ingestion

In the recent time, several in vitro and in vivo studies have shown the inh ibitory effect of grapefruit juice on metabolism of xenobiotics catalyzed b y liver oxidative enzymes including cytochrome P450 izoenzymes. However, al l these experiments were done with a single dose of grapefruit juice. The p rimary aim of this study was to evaluate if the chronical ingestion of grap efruit juice can cause enzyme activity alteration as well as a single dose. Three groups of male mice were used: the control group, the group which wa s administered 0.2 mL, of grapefruit juice per os 10 days and the group whi ch was administered single dose of 0.5 mL, grapefruit juice per os 90 min. before the sacrificing. After the sacrificing of animals, liver was homogen ized with appropriate buffer, and the activity of oxidative liver enzymes: xanthine oxidase (XOD), peroxidase (Px), catalase (CAT), lipid peroxidase ( LPx), glutathion peroxidase (GSH-Px) and liver glutathion contents (GSH) we re detected by standard methods. The results show that the enzyme activity of liver MFO was changed according to a single or multiple grapefruit juice ingestion. The grapefruit juice in a single oral dose significantly decrea ses the activity of xanthine oxidase, glutathion peroxidase, lipid peroxida se and liver glutathion contents, and has no effect on activity of catalase and peroxidase. The multiple grapefruit ingestion increases the activity o f XOD, GSH-Px, LPx, Pr and GSH, while the activity of CAT enzyme is unchang ed. The chronical and single grapefruit ingestion has no effect on relative liver weight, but the liver protein content is significantly decreased aft er the multiple oral grapefruit juice ingestion.