The potential protective effects of
oleuropein, a dietary
antioxidant of
olive oil, has been investigated in the isolated rat heart. The organs were subjected to 30 minutes of no-flow global
ischemia and then reperfused. At different time intervals, the coronary effluent was collected and assayed for
creatine kinase activity as well as for reduced and
oxidized glutathione. In addition, the extent of lipid peroxidation was evaluated by measuring
thiobarbituric acid reactive substance concentration in cardiac muscle. Pretreatment with 20 microg/g
oleuropein before
ischemia resulted in a significant decrease in
creatine kinase and
reduced glutathione release in the perfusate. The protective effect of
oleuropein against the post-ischemic oxidative burst was investigated by measuring the release, in the coronary effluent, of
oxidized glutathione, a sensitive marker of heart's exposure to oxidative stress. Reflow in ischemic hearts was accompanied by a prompt release of
oxidized glutathione; in ischemic hearts pretreated with
oleuropein, this release was significantly reduced.
Membrane lipid peroxidation was also prevented by
oleuropein. The reported data provide the first experimental evidence of a direct cardioprotective effect of
oleuropein in the acute events that follow
coronary occlusion, likely because of its
antioxidant properties. This finding strengthens the hypothesis that the nutritional benefit of
olive oil in the prevention of
coronary heart disease can be also related to the high content of
oleuropein and its derivatives. Moreover, our data, together with the well documented antithrombotic and antiatherogenic activity of
olive oil polyphenols, indicate these
antioxidants as possible therapeutic tools for the pharmacological treatment of
coronary heart disease as well as in the case of cardiac surgery, including
transplantation.