Oleuropein, an active constituent of olive oil and olive leaf, was investigated by Coni and coworkers1. The researchers conducted an in vivo study that evaluated oleuropein’s effects on the serum low density lipoprotein (LDL) levels in rabbits. The study was carried out on the basis of the positive results obtained with in vitro, pilot studies on human LDL. The results of these pilot studies indicated that certain constituents in olive oil inhibited prooxidative processes in human LDL.
The rabbits were fed special diets. Diet A consisted of a standard diet for rabbits. Diet B consisted of the standard diet plus 10% (w/w) extra virgin olive oil, and Diet C consisted of the standard diet plus 10% (w/w) extra virgin olive oil and 7 mg/kg oleuropein. In order to evaluate oleuropein’s effect, biochemical parameters identified in the rabbits’ blood plasma and LDL were measured before and after copper-induced oxidation.
The results verified the antioxidant efficacy of extra virgin olive oil’s biophenols, particularly oleuropein. In measuring the presence of conjugated dienes in the rabbits’ LDL, it was determined that rabbits fed Diet C had a lesser amount of conjugated dienes and therefore of lipid radicals than either rabbits fed Diets A or B. The amounts of conjugated dienes present in the LDL were 51.0 ± 9.3 µM, 25.8 ± 4.1 µM, and 19.8 ± 3.9 µM for rabbits fed Diet A, Diet B, and Diet C, respectively. Similarly, evaluation of other ox-LDL (oxidized LDL) parameters followed the same trend. These results indicate that oleuropein increased the ability of LDL to resist oxidation.
In addition to oleuropein’s antioxidant properties, it was determined that Diet C reduced the rabbits’ plasma levels of total, free, and ester cholesterol by 15%, 12%, and 17%, respectively, compared to rabbits fed Diet B. This reduction caused a redistribution of the lipid components of LDL with an indirect effect on the dimensions.
Source:
- Coni, E. et al. (2000) Protective effect of oleuropein, an olive oil biophenol, on low density lipoprotein oxidizability in rabbits. Lipids 35(1), 45-54
- Sabinsa supplies olive leaf extract standardized for a minimum of 12.5% oleuropein. Also, 80% oleuropein is available
