Lavelli Vera
DISTAM, Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche, Universitá degli Studi di Milano, via Celoria 2, I-20133 Milano, Italy.
J Agric Food Chem. 2002 Dec 18;50(26):7704-8. doi: 10.1021/jf020749o.
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.
对不同产地和降解程度的特级初榨橄榄油（EVOOs）的酚类含量和抗氧化活性进行了研究。采用高效液相色谱法分析了橄榄油特有的邻二酚类化合物，即橄榄苦苷衍生物羟基酪醇（3',4'-二羟基苯乙醇，3',4'-DHPEA）、与3',4'-DHPEA相连的elenolic酸的二醛形式（3',4'-DHPEA-EDA）以及橄榄苦苷苷元的一种异构体（3',4'-DHPEA-EA）。通过以下方法研究抗氧化活性：（a）黄嘌呤氧化酶（XOD）/黄嘌呤系统，该系统产生超氧自由基和过氧化氢；（b）心肌黄酶（DIA）/烟酰胺腺嘌呤二核苷酸（NADH）/胡桃醌系统，该系统产生超氧自由基和半醌自由基；（c）2,2-二苯基-1-苦基肼自由基（DPPH）试验。结果表明，与中度和高度降解水平的油相比，降解水平低的特级初榨橄榄油（根据欧盟法规通过酸度、过氧化值和光谱指数K(232)、K(270)和δK评估）具有更高的3',4'-DHPEA-EDA含量和更低的3',4'-DHPEA含量。与中度和高度降解水平的油相比，降解程度低 的特级初榨橄榄油作为DPPH清除剂的效率高3至5倍，作为XOD催化反应抑制剂的效率高2倍。低或中度降解水平的特级初榨橄榄油可抑制DIA催化的反应，但最降解的油则不能。
