title: Comparison of the antioxidant activities of extra virgin olive oils.
abstract: The phenol content and antioxidant activity of extra virgin olive oils (EVOOs) differing in their origins and degradation degrees were studied. The o-diphenolic compounds typical of olive oil, namely, the oleuropein derivatives hydroxytyrosol (3',4'-dihydroxyphenylethanol, 3',4'-DHPEA), the dialdehydic form of elenolic acid linked to 3',4'-DHPEA (3',4'-DHPEA-EDA), and an isomer of oleuropein aglycon (3',4'-DHPEA-EA), were analyzed by HPLC. The antioxidant activity was studied by (a) the xanthine oxidase (XOD)/xanthine system, which generates superoxide radical and hydrogen peroxide; (b) the diaphorase (DIA)/NADH/juglone system, which generates superoxide radical and semiquinonic radical; and (c) the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) test. Results showed that EVOOs with a low degradation level (as evaluated by acidity, peroxide number, and spectroscopic indices K(232), K(270), and deltaK according to the EU Regulation) had a higher content of 3',4'-DHPEA-EDA and a lower content of 3',4'-DHPEA than oils having intermediate and advanced degradation levels. EVOOs with a low degradation degree were 3-5 times more efficient as DPPH scavengers and 2 times more efficient as inhibitors of the XOD-catalyzed reaction than oils with intermediate and advanced degradation levels. The DIA-catalyzed reaction was inhibited by EVOOs having low or intermediate degradation levels but not by the most degraded oils.
authors.affiliation: DISTAM, Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche, Universitá degli Studi di Milano, via Celoria 2, I-20133 Milano, Italy. vera.lavelli@unimi.it
authors.forename: Vera
authors.initials: V
authors.lastname: Lavelli
mesh_terms: D000975:Antioxidants / Q000032:analysis* / Q000494:pharmacology; D016227:Benzoquinones / Q000737:chemistry; D001713:Biphenyl Compounds; D002851:Chromatography, High Pressure Liquid; D008058:Dihydrolipoamide Dehydrogenase; D006861:Hydrogen Peroxide / Q000737:chemistry; D009285:Naphthoquinones; D000069463:Olive Oil; D010636:Phenols / Q000032:analysis / Q000494:pharmacology; D010851:Picrates / Q000737:chemistry; D010938:Plant Oils / Q000737:chemistry*; D013481:Superoxides / Q000737:chemistry; D019820:Xanthine; D014969:Xanthine Oxidase
chemical_list: D000975:Antioxidants; D016227:Benzoquinones; D001713:Biphenyl Compounds; D009285:Naphthoquinones; D000069463:Olive Oil; D010636:Phenols; D010851:Picrates; D010938:Plant Oils; D013481:Superoxides; D019820:Xanthine; C025232:semiquinone radicals; D006861:Hydrogen Peroxide; C004931:1,1-diphenyl-2-picrylhydrazyl; D014969:Xanthine Oxidase; D008058:Dihydrolipoamide Dehydrogenase; C005134:juglone