Radical-Scavenging Compounds from Olive Tree (Olea europaea L.) Wood

The purpose of this study was to complete knowledge on the chemical composition and radical-scavenging activity of olive tree wood. Two new monoterpene glycosides, (-)-oleuropeic acid 6'-O-alpha-D-glucopyranosyl ester (6a) and (-)-perillic acid 1'-O-beta-6-primeverosyl ester (8), together with the known compounds (-)-oleuropeic acid (1), (-)-olivil (2), the aldehydic form of oleuropein aglycone (3), (+)-1-hydroxypinoresinol 1-O-beta-D-glucopyranoside (4), (-)-oleuropeic acid 1'-O-beta-n-glucopyranosyl ester (5), (-)-oleuropeic acid 6'-O-beta-D-glucopyranosyl ester (6b), and (-)-olivil 4-O-beta-n-glucopyranoside (7) were isolated from an ethyl acetate extract. The radical scavengers found (2-4 and 7) were detected and isolated with the help of the online HPLC-DAD-DPPH/ABTS technique. Compounds 2-4 and 7 displayed a higher antioxidative effect against the free radical DPPH than the reference BHT and lower than hydroxytyrosol, whereas compounds 1, 5, 6a, 6b, and 8 showed no activity.