Synthesis of Tritium-Labeled Hydroxytyrosol, a Phenolic Compound Found in Olive Oil

(3,4-Dihydroxyphenyl)ethanol, commonly known as hydroxytyrosol (1), is the major phenolic antioxidant compound in olive oil, and it contributes to the beneficial properties of olive oil. Bioavailability and metabolism studies of this compound are extremely limited, in part, related to unavailability of radiolabeled compound. Studies with radiolabeled compounds enable use of sensitive radiometric analytical methods as well as aiding elucidation of metabolic and elimination pathways. In the present study a route for the formation of hydroxytyrosol (1), by reduction of the corresponding acid 2 with tetrabutylammonium boronate, was found. Methods for the incorporation of a tritium label in 1 were investigated and successfully accomplished. Tritiated hydroxytyrosol (1t) was synthesized with a specific activity of 66 Ci/mol. The stability of unlabeled and labeled hydroxytyrosol was also investigated.