Effect of experimental factors on the prooxidant behavior of α‐tocopherol

Abstract

We have investigated the effect of experimental factors on the prooxidant effect of α‐tocopherol during the autoxidation of linoleic acid. The prooxidant effect depended on two factors: the concentration of α‐tocopherol (≥ 5 x 10−3 mol α‐tocopherol/1 mol linoleic acid) and the solvent, an aqueous system in which the prooxidant effect occurred more easily. On the other hand, the prooxidant behavior of α‐tocopherol was unaffected by the type of surfactant used in water as well as by the presence of different salts. The initial content of hydroperoxides affected the intensity of the prooxidant effect which varied in an inverse ratio to the initial hydroperoxide level.

Why is the order reversed? peroxyl‐scavenging activity and fats‐and‐oils protecting activity of vitamin E

“…Similar gradual weight gains were also observed for ␤-and ␥ -Toc's, although those were less than that for ␣-Toc. These weight gains come from pro-oxidant effect of Toc, which leads to an increase of LOOH [21][22][23][24][25][26].…”

The Mechanism of Antioxidant Action in Vitro

“…Often the antioxidant activity of phenolic antioxidants is lost at high concentrations and they may become pro-oxidant. 27 This is due to their involvement in initiation reactions such as (26) or (27) at high concentrations. 28 AH + 02~ A' + HOO' AH+ROOH~RO' +H20+A' (26) (27) Antioxidant action by donation of a hydrogen atom is unlikely to be limited to phenols.…”

Mécanismes de la peroxydation lipidique et des anti-oxydations

“…L'effet prooxydant de l'acide ascorbique en présence de fer est bien documenté. De même nous avons mis en évidence un effet prooxydant de l'alpha tocophérol à fortes concentrations [19,20]. Les flavonoïdes comme la quercétine et la myricétine peuvent également présenter des propriétés pro-oxydantes [21].…”