Polyphenols as antioxidants

The effectiveness of tea polyphenols as antioxidants in elastomeric mixes was evaluated and comparison was made with standard styrenated phenol-based antioxidant [45]. The data showed that thermal and oxidative aging resistance was comparable for both natural and synthetic antioxidants. 

Lotito SB and Frei B. 2004. Relevance of apple polyphenols as antioxidants in human plasma contrasting in vitro and in vivo effects. Free Radic Biol Med 36(2) 201—211. 

POLYPHENOLS AS ANTIOXIDANTS Polyphenols as Chain-Breaking Antioxidants... 

FDA s Antioxidant Guidance Is This the End of the Road for Marketing Polyphenols as Antioxidants Nutraceuticals World, March 2009. nutraceuticalsworld.com/articles/2009/03/new-roles-for-polyphenols. 

Rice-Evans C. Implications of the mechanisms of action of tea polyphenols as antioxidants in vitro for chemoprevention in humans. Proc Soc Exp Biol Med 1999 220 262-266. 

Chemical Antioxidant Systems. The antioxidant activity of tea extracts and tea polyphenols have been determined using in vitro model systems which are based on hydroxyl-, peroxyl-, superoxide-, hydrogen peroxide-, and oxygen-induced oxidation reactions (109—113). The effectiveness of purified tea polyphenols and cmde tea extracts as antioxidants against the autoxidation of fats has been studied using the standard Rancimat system, an assay based on air oxidation of fats or oils. A direct correlation between the antioxidant index of a tea extract and the concentration of epigallocatechin gallate in the extract was found (107). 

Animal studies have shown that teas are effective in blocking or slowing carcinogenesis (121,131,133). Administration of teas or tea polyphenols to mice or rats have also been shown to decrease oxidative biomarkers, suggesting that tea polyphenols act as antioxidants (125,134). 

SRB contains high-quality protein, oil, dietary fiber, polysaccharides, fat-soluble phytochemicals (plant derived bioactive compounds) and other bran nutrients. Rice bran and germ are the richest natural sources of B complex vitamins as well as E vitamins, polyphenols, several antioxidants and minerals. It is now available in the commercial food ingredient market as a safe and effective functional food and dietary supplement. 

Pulido R, Bravo L and Saura-Calixto, F. 2000. Antioxidant activity of dietary polyphenols as determined by a modified ferric reducing/antioxidant power assay. J Agric Food Chem 48(8) 3396-3402. 

Polyphenols can act as antioxidants by a number of potential pathways. The most important is likely to be by free radical scavenging, in which the polyphenol can break the radical chain reaction. Polyphenols are effective antioxidants in a wide range of chemical oxidation systems, being capable of scavenging peroxyl radicals, alkyl peroxyl radicals, superoxide, hydroxyl radicals, nitric oxide and peroxynitrate in aqueous and organic environments [121]. This activity is due to the ability of donating an H atom from an aromatic hydroxyl group to a free radical, and the major ability of an aromatic structure to support an unpaired electron by delocalization around the 7i-electron system. Phenolic acids... 

Dr. Joe Vinson of the University of Scranton believes that there is something to the chocolate effect, and he came to Belmont to tell us about his intriguing research. Vinson has determined the total polyphenol content of various chocolates and has also found a way of measuring how effective these mixtures are in preventing the oxidation of human ldl in a test tube. In other words, he has calculated a phenol antioxidant index, which takes into account both the quantity and the quality of these desirable substances. At the symposium Vinson reported that cocoa powder and dark chocolate are the best, followed by milk chocolate. Instant cocoa mixes trail the field. Then Vinson delivered the kicker chocolate has more, and better, polyphenols than fruits or vegetables and more than red wine. A forty-gram bar of dark chocolate has as many polyphenols as a cup of that widely promoted antioxidant cocktail we call tea. But there is still the matter of chocolate s fat content. Researchers tell us, though, that at least half of it is stearic acid, which does not raise blood cholesterol. 

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