Dietary Caffeic Acid, Ferulic Acid and Coumaric Acid Supplements on Cholesterol Metabolism and Antioxidant Activity in Rats

This study was designed to test the lipid-lowering and antioxidative activities of three phenolic compounds, caffeic acid, ferulic acid and coumaric acid. Four groups of rats were given a semisynthetic diet containing 3% of cholesterol for 6 weeks. The control group only received a high cholesterol diet, whereas the other three groups received a diet including 0.2% of caffeic acid, 0.2% of ferulic acid and 0.2% of coumaric acid. The caffeic acid, ferulic acid and coumaric acid significantly lowered the plasma lipid and hepatic cholesterol levels compared to those in the control (p < 0.05). The hepatic HMG-CoA reductase activity was significantly lower in the caffeic acid group than in the ferulic acid and coumaric acid groups (p < 0.05), while the hepatic ACAT activity was significantly lower in the caffeic acid, ferulic acid and coumaric acid groups compared to the control group (p < 0.05). The overall potential of the antioxidant system was significantly enhanced by the caffeic acid, ferulic acid and coumaric acid supplements as the plasma and hepatic TBARS levels were lowered while the hepatic SOD activities and GSH concentration were elevated in the high-cholesterol-fed rats (p < 0.05). Furthermore, these results indicated that the supplementation of caffeic acid, ferulic acid and coumaric acid boosted the antioxidant activity in rats and promoted the excretion of neutral sterol and acidic sterol (p < 0.05), thereby leading to a decreased absorption of dietary cholesterol as well as lower plasma, hepatic cholesterol and promoted excretion of fecal sterols.