linoleic-acid and epicatechin-gallate

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 alpha-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.

Topics: alpha-Tocopherol; Antioxidants; Ascorbic Acid; Catechin; Complex Mixtures; Flavonoids; Free Radicals; Half-Life; Kinetics; Linoleic Acid; Lipid Peroxidation; Micelles; Phenols; Polyphenols; Sodium Dodecyl Sulfate; Tea

Chinese water chestnut (CWC) is one of the most popular foods among Asian people due to its special taste and medical function. Experiments were conducted to test the antioxidant activity and then determine the major phenolic compound components present in CWC. CWC phenolic extract strongly inhibited linoleic acid oxidation and exhibited a dose-dependent free-radical scavenging activity against alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radicals, superoxide anions and hydroxyl radicals, which was superior to ascorbic acid and butylated hydroxytoluene (BHT), two commercial used antioxidants. Furthermore, the CWC extract was found to have a relatively higher reducing power, compared with BHT. The major phenolic compounds present in CWC tissues were extracted, purified and identified by high-performance liquid chromatograph (HPLC) as (-)-gallocatechin gallate, (-)-epicatechin gallate and (+)-catechin gallate. This study suggests that CWC tissues exhibit great potential for antioxidant activity and may be useful for their nutritional and medicinal functions.

Topics: Antioxidants; Biphenyl Compounds; Butylated Hydroxytoluene; Catechin; Chemistry; Chromatography, High Pressure Liquid; Dose-Response Relationship, Drug; Eleocharis; Free Radicals; Hydrazines; Linoleic Acid; Lipid Peroxidation; Models, Chemical; Phenol; Picrates