Hydroxytyrosol, as a component of olive mill waste water, is dose-dependently absorbed and increases the antioxidant capacity of rat plasma

Hydroxytyrosol is the most potent phenolic antioxidant of olive oil and oli ve mill waste water (OMWW) and its biological activities have stimulated re search on its potential role in cardiovascular protection. However, evidenc e of the absorption of OMWW phenolics and on their possible in vivo activit y has, until now, never been provided. Three groups male Sprague-Dawley rat s were administered 1, 5, or 10 mg/Kg of the OMWW extract, respectively, pr oviding 41.4, 207, and 414 mug/Kg of hydroxytyrosol, respectively. Urine wa s collected for 24 h and the urinary levels of hydroxytyrosol were quantifi ed by mass spectrometry. Hydroxytyrosol was dose-dependently (R-2=0.95) abs orbed and excreted in the urines mostly as a glucuronide conjugate. Further , the administration of an hydroxytyrosol-rich OMWW extract (10 mg/kg) to t he rats was also associated with an increase of their plasma antioxidant ca pacity. Future experiments will eventually further clarify its metabolic fa te and its in vivo actions.