Hydroxytyrosyl acetate contributes to the protective effects against oxidative stress of virgin olive oil

The effects of virgin olive oil phenols, hydroxytyrosyl acetate (HTy-Ac) and hydroxytyrosol (HTy), on cell integrity and steady-state values of cellular redox status were assessed in HepG2 cells, as well as their potential protective effects against oxidative stress induced by tert-butyl hydroperoxide (t-BOOH). Direct treatment for 20 h with 0.5-10 mu M HTy or HTy-Ac reduced ROS generation and increased glutathione peroxidase activity at the higher concentrations. Furthermore, after t-BOOH exposure, pretreatment with HTy-Ac and HTy for 2 or 20 h counteracted cell viability damage from 1 mu M, counterbalanced reduced glutathione levels from 0.5 mu M, protected against lipid peroxidation from 0.5 mu M, decreased ROS generation from 1 mu M as well as antioxidant enzyme activities from 1 mu M. All these changes were statistically significant. HTy-Ac presents antioxidative stress protective effects at physiological concentrations similar to or even slightly higher than that of HTy, thus contributing to the protective role of virgin olive oil. (C) 2011 Elsevier Ltd. All rights reserved.