Hypocholesterolemic effects of phenolic-rich extracts of Chemlali olive cultivar in rats fed a cholesterol-rich diet

This study was designed to test the lipid-lowering and the antioxidative activities of green and black olive phenolic extracts. Wistar rats fed a standard laboratory diet or a cholesterol-rich diet for 16 weeks were used. The serum lipid levels, the malondialdehyde (MDA) and the activity of superoxide dismutase (SOD) as well as that of catalase (CAT) were examined. The cholesterol-rich diet induced hypercholesterolemia that was manifested in the elevation of total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C). Administration of aqueous methanol and ethyl acetate extracts of green olives and ethyl acetate extract of black olives significantly lowered the serum levels of TC and LDL-C, while increasing the serum level of high density lipoprotein cholesterol (HDL-C). Furthermore, the content of MDA in liver, heart and kidney decreased significantly after oral administration of green and black olive extracts compared with those of rats fed a cholesterol-rich diet. In addition, olive extracts increased CAT and SOD activities in liver. These results suggested that the hypocholesterolemic effect of green and black olive extracts might be due to their abilities to lower serum cholesterol level as well as to slow down the lipid peroxidation process and to enhance the antioxidant enzyme activity.