Alternative Biomimetic Method to Obtain Oleacein, an Important Metabolite of Olive (Olea europaea, L.)

The present study proposes an alternative protocol to obtain oleacein, an important metabolite of olive with relevant organoleptic and nutritional properties, using a biomimetic approach with demethyloleuropein as the starting substrate. Demethyloleuropein was obtained at a purity of at least 70\% from extracts of black ripe olives in boiling ethanol at 80\%. Enzymatic extracts were obtained from several olive samples and further subjected to cold storage for up to 30 days at 4 °C or frozen at −20 °C to evaluate the effect of storage conditions. The endogenous glucosidase activity of olive drupes, obtained by the decanted supernatant of a 1:1 w/v mixture of cold olive pulp with cold acetate buffer 0.2 M, pH 4.6, was assayed in a buffered solution at pH 4.6. Reactions were carried out at 20 °C for 1 h in the presence of chloroform under stirring to extract the aglycones as they were formed. Higher yields of up to 48\% were obtained when fresh black olive drupes of the Leccino cultivar were used. Significant decreases in enzymatic activity were observed in both cold-stored and frozen olives. High yields were also obtained using a very high concentration of commercial β-glucosidase (150 U/mL), suggesting the presence of specific enzymes in olive tissues.