Antioxidant synergism of green tea polyphenols with α-tocopherol and l-ascorbic acid in SDS micelles

The synergistic antioxidant effect of polyphenols extracted from green tea, i.e. (−)-epicatechin (EC), (−)-epigallocatechin (EGC), (−)-epicatechin gallate (ECG), (−)-epigallocatechin gallate (EGCG) and gallic acid (GA), with α-tocopherol (vitamin E) and l-ascorbic acid (vitamin C) against the peroxidation of linoleic acid has been studied in sodium dodecyl sulfate (SDS) micelles. The peroxidation was initiated thermally by a water-soluble azo initiator 2,2′-azobis(2-amidinopropane) hydrochloride (AAPH), and the reaction kinetics were studied by monitoring the formation of linoleic acid hydroperoxides and consumption of the antioxidants. It was found that the mixture of the green tea polyphenol, vitamin E and vitamin C could act synergistically to protect lipid peroxidation. Kinetic and mechanistic studies on the antioxidation process revealed that this antioxidant synergism was due to the regeneration of vitamin E by the green tea polyphenol and the regeneration of the latter by vitamin C.