Antioxidant activity of the main bioactive derivatives from oleuropein hydrolysis by hyperthermophilic beta-glycosidase

The main reaction products obtainable by the hydrolysis of commercially ava ilable oleuropein by hyperthermophilic beta -glycosidase were purified and structurally characterized by UV and H-1 and C-13 NMR analyses. Their antio xidant activity, in particular their capacity to inhibit the fatty acid per oxidation rate, was studied. The molecular structures assigned revealed the presence of two elenolic acid forms presenting different antioxidant abili ties closely correlated to their molecular structures, as well as an unstab le elenolate which is a rearrangement product of the oleuropein aglycon. Th is molecule, under the reaction conditions (pH 7.0, 60 degreesC) required f or beta -glycosidase activity, rapidly gives rise to 3,4-dihydroxy-phenylet hanol (hydroxytyrosol).