Inhibitory and synergistic effects of natural olive phenols on human platelet aggregation and lipid peroxidation of microsomes from vitamin E-deficient rats

This study explored the in vitro antioxidant and anti-platelet activities of hydroxytyrosol, hydroxytyrosol acetate, 3,4-dihydroxyphenylglycol and two phenolic olive extracts. These compounds and extracts were obtained from a new industrial process to hydrothermally treat the alperujo (160 A degrees C/60 min), a by-product of olive oil extraction. The extracts and the purified compounds were obtained chromatographically using both ionic and adsorbent resins. The antioxidant activity was determined by measuring inhibition of human platelet aggregation and inhibition of lipid peroxidation in liver microsomes of vitamin E-deficient rats. The positive effect of the extracts on the inhibition of platelet aggregation is showed, being higher in the case of hydroxytyrosol acetate up to 38 %, and for the first time, its synergist effect with hydroxytyrosol has been proved, obtaining more than double of inhibition. The phenolic extracts and the isolated phenols showed good results for inhibiting the lipid oxidation, up to 62 and 25 %, respectively. A synergistic effect occurred when the hydroxytyrosol acetate and the 3,4-dihydroxyphenylglycol were supplemented by hydroxytyrosol. These results suggest the extract and these compounds obtained from a novel industrial process could be natural alternatives for the prevention of diseases related to cardiovascular disorder or oxidative damage.