Publication details

Influence of dietary phenolic acids on redox status of iron: Ferrous iron autoxidation and ferric iron reduction

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Year of publication 2008
Type Article in Periodical
Magazine / Source Food Chemistry
MU Faculty or unit

Faculty of Medicine

Field Food production
Keywords Iron; Phenolic acids; Polyphenols; Ferrous ion; Ferric ion; Autoxidation; Ferric iron reduction; Metal chelation; Ferroxidase-like activity
Description All phenolic acids bearing 3,4-dihydroxy (catechol) or 3,4,5-trihydroxy (galloyl) moiety formed chelates with ferric iron and significantly increased the rate of Fe2+ autoxidation. The carboxylate group and catechol substitution instead of galloyl moiety facilitated the ferrous ion oxidation more effectively. Caffeic acid and protocatechuic acid, the strongest accelerators of Fe2+ autoxidation, were able to facilitate autoxidation at concentrations lower than 1% of the initial amount of Fe2+. Therefore chelates of these catecholic acids with iron displayed ferroxidase-like activity. Conversely, when we started from ferric ions, catechols partially formed ferrous ions in the presence of ferrozine. Thus, catecholic acids formed stable chelates with iron, in which ferric ion is the dominant species, but the redox cycling of iron between Fe2+ and Fe3+ in chelates probably plays a crucial role in the catalysis of ferrous iron autoxidation. Interestingly, 3-hydroxybenzoic acid, 4-hydroxybenzoic acid and vanillic (4-hydroxy-3-methoxybenzoic) acid protected ferrous ions from autoxidation as effectively as ascorbic acid and cysteine.
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