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Behavior of phenolic antioxidants in a partitioned medium: structure—Activity relationship

2000; Wiley; Volume: 77; Issue: 8 Linguagem: Inglês

10.1007/s11746-000-0131-4

1558-9331

Marie‐Elisabeth Cuvelier, Vincent Bondet, Claudette Berset,

Antioxidant Activity and Oxidative Stress

Abstract The behavior of phenolic antioxidants is studied in a partitioned medium, composed of linoleic acid dispersed in an aqueous phase. Their efficiency is measured by the diene production during oxidation, induced by Fe (II)/ascorbic acid at 30°C. With a linoleic acid/Fe 2+ molar ratio of 10 and a Fe 2+ /ascorbic acid molar ratio of 23, a steady‐state propagation rate is reached after 1 h for up to 15 h. The antioxidants cannot avoid the early dienes (30–40% of total dienes), resulting from the inducing reactions; however, they can stop all the dienes produced during propagation reactions by acting on ROO . The inhibition values reveal a great difference between the antioxidants, depending on their structure (number of hydroxyl groups or chelating sites) and on their polarity, confirming the “polar paradox”. Thus, α‐tocopherol, butylated hydroxytoluene, butylated hydroxyanisole, and isoeugenol appear to be the best antioxidants, but rosmarinic and caffeic acids, generally potent antioxidants, present a weak efficiency. Surprisingly, in such a metal‐induced system, the chelator activity seems to play a minor role.