Antioxidattive activities of Olea europaea leaves and related phenolic compounds
1992
Le Tutour, B. | Guedon, D.
Olea europaea leaves, oleuropein, hydroxytyrosol and tyrosol were compared with vitamin E and BHT, with regard to their antioxidative activities, by kinetic studies in model systems. The thermal initiated oxidation of methyl linoleate was performed in homogeneous solution at 60 degrees or 40 degrees with or without antioxidants. Olea europaea extracts, oleuropein and hydroxytyrosol were much more effective than BHT or vitamin E in extending the induction period. Assuming a stoichiometric factor f=2 for BHT, this coefficient of inhibition reached 5 for hydroxytyrosol, 7 for oleuropein and 10 for 0. europaea extracts. These extracts owe their antioxidative properties to their high oleuropein content (19% w/w) and also to a lesser amount of flavonoids (1.8% w/w with 0.8% of luteolin 7-glucoside). Tyrosol showed neither antioxidant nor prooxidant activity. No synergistic effect on the preservation of methyl linoleate was found when vitamin E was used together with tyrosol or O. europaea extracts.
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