CONTRIBUTION OF TYROSOL AND ETHANOL TO THE IN VIVO ENDOGENOUS FORMATION OF HYDROXYTYROSOL IN HUMANS

Hydroxytyrosol [2-(3,4-dihydroxyphenyl)ethanol] is a potent bioactive molecule with multiple health benefits that is present in olive oil and wine. In humans, ethanol intake induces the formation of small amounts of hydroxytyrosol through the alteration of dopamine metabolism (1). In rats, tyrosol is converted into hydroxytyrosol. It has been postulated that wine components (specifically tyrosol and ethanol) act synergistically generating important amounts of hydroxytyrosol (2). The aim of this study was to assess the contribution of tyrosol and/or ethanol on hydroxytyrosol recovery in the urine of healthy volunteers. The effect of white wine (WW; a source of ethanol with low phenolic content) and/or pure tyrosol on the urinary excretion of total hydroxytyrosol was evaluated. Tyrosol, hydroxytyrosol and their metabolites were quantified by LC-MS/MS. Results showed that (i) WW increased hydroxytyrosol urinary recovery, (ii) pure tyrosol also increased this recovery, and (iii) the combination of WW+tyrosol resulted in an exponential increase of hydroxytyrosol. These data demonstrates the in vivo formation of hydroxytyrosol from tyrosol in humans and evidences the synergistic effect of ethanol and tyrosol on hydroxytyrosol endogenous formation. These results open a new venue in our understanding of health beneficial effects associated to the intake of moderate doses of wine.