Effect of rutin and tannic acid supplements on cholesterol metabolism in rats

This study was designed to test the lipid-lowering and antioxidative activities of two phenolic compounds, rutin and tannic acid. Three groups of rats were given a semisynthetic diet containing 1 g of cholesterol/kg for 5 wks. The control group only received a high cholesterol diet, whereas the other two groups received a diet including 1 g of rutin or 1 g of tannic acid/kg. The rutin and tannic acid both significantly lowered the plasma lipid and hepatic cholesterol levels compared to those in the control. The hepatic HMG-CoA reductase activity was significantly lower in the tannic acid group than in the rutin group, while the hepatic ACAT activity was significantly lower in both the rutin and tannic groups compared to the control group. The overall potential of the antioxidant system was significantly enhanced by the rutin and tannic acid supplements as the plasma and hepatic TBARS levels were lowered while the hepatic SOD and GSH-Px activities were increased in the high-cholesterol fed rats. Furthermore, these results suggest that the supplementation of rutin and tannic acid promoted the excretion of fecal sterols, thereby leading to a decreased absorption of dietary cholesterol as well as lower plasma and hepatic cholesterol.