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 K232, K270, 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.
|Titolo:||Comparison of the antioxidant activities of extra virgin olive oils|
LAVELLI, VERA AGNESE (Primo)
|Parole Chiave:||2,2-diphenyl-1-picrylhydrazyl radical; Diaphorase; Extra virgin olive oil; Oleuropein derivatives; Xanthine oxidase|
|Settore Scientifico Disciplinare:||Settore AGR/15 - Scienze e Tecnologie Alimentari|
|Data di pubblicazione:||2002|
|Digital Object Identifier (DOI):||10.1021/jf020749o|
|Appare nelle tipologie:||01 - Articolo su periodico|