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Interactions of ferric ions with olive oil phenolic compounds

Paiva-Martins, F. and Gordon, M.H. (2005) Interactions of ferric ions with olive oil phenolic compounds. Journal of Agricultural and Food Chemistry, 53 (7). pp. 2704-2709. ISSN 0021-8561

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To link to this item DOI: 10.1021/jf0481094

Abstract/Summary

The ferric complexing capacity of four phenolic compounds, occurring in olives and virgin olive oil, namely, oleuropein, hydroxytyrosol, 3,4-dihydroxyphenylethanol-elenolic acid (3,4-DHPEA-EA), and 3,4-dihydroxyphenylethanol-elenolic acid dialdehyde (3,4-DHPEA-EDA), and their stability in the presence of ferric ions were studied. At pH 3.5, all compounds formed a reversible 1:1 complex with ferric ions, but hydroxytyrosol could also form complexes containing > 1 ferric ion per phenol molecule. At pH 5.5, the complexes between ferric ions and 3,4-DHPEA-EA or 3,4-DHPEA-EDA were relatively stable, indicating that the antioxidant activity of 3,4-DHPEA-EA or 3,4-DHPEA-EDA at pH 5.5 is partly due to their metal-chelating activity. At pH 7.4, a complex containing > 1 ferric ion per phenol molecule was formed with hydroxytyrosol. Oleuropein, 3,4-DHPEA-EA, and 3,4-DHPEA-EDA also formed insoluble complexes at this pH. There was no evidence for chelation of Fe(II) by hydroxytyrosol or its derivatives. At all pH values tested, hydroxytyrosol was the most stable compound in the absence of Fe(III) but the most sensitive to the presence of Fe(III).

Item Type:Article
Refereed:Yes
Divisions:Faculty of Life Sciences > School of Chemistry, Food and Pharmacy > Department of Food and Nutritional Sciences
ID Code:13100
Uncontrolled Keywords:antioxidants, hydroxytyrosol, Olea europaea, oleuropein, iron, polyphenols, olive oil, 3,4-DHPEA-EA, 3,4-DHPEA-EDA, IN-WATER EMULSIONS, ANTIOXIDANT ACTIVITY, OLEA-EUROPAEA, RIPE OLIVES, PH, OXIDATION, POLYPHENOLS, COMPLEXES, SYSTEMS, IRON

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