Antioxidant activity of hydroxytyrosol acetate compared with that of otherolive oil polyphenols

Hydroxytyrosol acetate was synthesized, and the antioxidant activity of thi s olive oil component was assessed in comparison with that of other olive o il components, namely hydroxytyrosol, oleuropein, 3,4-DHPEA-EA, and alpha - tocopherol in bulk oil and oil-in-water emulsions. The activity of the comp ounds was also assessed by scavenging of 1,1-diphenyl-2-picrylhydrazyl (DPP H) radicals. Hydroxytyrosol acetate had a weaker DPPH radical scavenging ac tivity than hydroxytyrosol, oleuropein, or 3,4-DHPEA-EA but it had a radica l scavenging activity similar to that of cr-tocopherol. In oil, the antioxi dant activity of hydroxytyrosol acetate was much higher than that of alpha -tocopherol or oleuropein, but in an emulsion S,4-DHPEA-EA and alpha -tocop herol were more effective as antioxidants than hydroxytyrosol acetate. The antioxidant activity of hydroxytyrosol acetate was rather similar to that o f hydroxytyrosol in oil and emulsions despite the difference in DPPH radica l scavenging activity.