Cardioprotective potential of oleuropein, hydroxytyrosol, oleocanthal and their combination: unravelling complementary effects on acute myocardial infarction and metabolic syndrome

Abstract Background/Introduction Clinical studies have established the role of olive products in primary and secondary prevention of cardiovascular (CV) disease, but the single compounds or compound combinations responsible for the protective effects are still under investigation. Purpose We sought to explore and compare the cardioprotective potential of Oleuropein (OL), Hydroxytyrosol (HT), Oleocanthal (OC) and Oleanolic Acid (OA) and three combinational treatments after chronic oral administration in mice subjected to Ischemia/Reperfusion Injury (IRI) in the presence of metabolic syndrome (MS) and verify the effect of combination in a proof-of-concept clinical study in Chronic Coronary Artery Syndrome (CCAS) patients. Methods First, we explored the IRI-limiting potential of 6-weeks daily oral treatment with OL (20.6 mg/kg), HT (5.9 mg/kg), OC (11.6 mg/kg), OA (17.4 mg/kg) or vehicle (DMSO 5%) in healthy C57Bl6 mice. At week 6, myocardial ischemia/reperfusion (30 minutes/2 hours) was induced and infarct size was measured. Next, MS was established by 14 weeks of Western diet and the isolated compounds were administered for the last 6 weeks. At week 14, IRI was surgically induced, and infarct size was determined. Basic MS parameters (fasting blood glucose, plasma cholesterol, body weight and blood pressure) were recorded at baseline, weeks 8 and 14. According to the exerted benefits, three combinational treatments were designed and tested on the MS model of IRI. The underlying cardioprotective mechanism was investigated on the mixture with preponderant CV benefits (OL-HT-OC, Combo 2). ApoE-/- mice fed with Western diet for 12 weeks were treated with Combo 2 orally for the last 4 weeks and aortic atherosclerotic lesion extent was determined to detect possible antiatherosclerotic effects. After multi-organ toxicity evaluation, a Combo 2-based supplement was administered in CCAS patients for evaluation of cardiac function, inflammation and oxidative stress biomarkers. Results OL, OC and OA, but not HT, significantly reduced infarct size in vivo both in healthy and MS mice. OL was the only compound to reduce hyperglycemia, while OA significantly reduced plasma cholesterol. All mixtures (Combo 1: OL-HT-OA, Combo 2: OL-HT-OC, Combo 3: OL-HT-OC-OA) were cardioprotective, but only Combo 2 prevented MS progression by limiting hyperglycemia. Combo 2 protection against IRI was attributed to apoptosis suppression (reduced Bax/BcL-xL ratio) and increased expression of the antioxidant enzymes Superoxide Dismutase and Catalase in the ischemic myocardium. Combo 2 treatment also reduced atherosclerotic lesion extent. In our proof-of-concept clinical study, Combo 2 treatment ameliorated cardiac, vascular and endothelial function in CCAS patients. Conclusions Combinational treatment with OL-HT-OC exerts potent cardioprotective, antihyperglycemic and antiatherosclerotic properties in vivo, with remarkable and clinically translatable CV benefits in high-risk patients.