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.