Flavonoids peroxyl radical-scavenging activity

Peroxyl Radical-Scavenging Activity of Flavonoids, Other Phenolic Compounds, and Unrefined Seed Oils... 

Figure 6. The peroxyl radical-scavenging activities of various vegetable oils (A) and flavonoid and phenolic compounds (B). Oils in markets. Adapted with permission from references 8 and 18, Copyrights 1999American Association for Cancer Research (A) and ACS (B),...

Dugas Jr. AJ, Castaneda-Acosta J, Bonin GC, Price KL, Fischer NH, Winston GW. Evaluation of the total peroxyl radical-scavenging capacity of flavonoids Structure-activity relationships. J Nat Prod. 

The total antioxidant activity of teas and tea polyphenols in aqueous phase oxidation reactions has been deterrnined using an assay based on oxidation of 2,2 -azinobis-(3-ethylbenzothiazoline-sulfonate) (ABTS) by peroxyl radicals (114—117). Black and green tea extracts (2500 ppm) were found to be 8—12 times more effective antioxidants than a 1-mAf solution of the water-soluble form of vitamin E, Trolox. The most potent antioxidants of the tea flavonoids were found to be epicatechin gallate and epigallocatechin gallate. A 1-mAf solution of these flavanols were found respectively to be 4.9 and 4.8 times more potent than a 1-mAf solution of Trolox in scavenging an ABT radical cation. 

Trans-resveratrol (trans-3,5,4 -trihydroxystilbene) is a non-flavonoid polyphenol found in grapes, mulberries, and other food prod-ucts. It is responsible for the antioxidant activity of red wine. Intake of moderate amount of red wine has been found to reduce the risk of cardiovascular diseases. In addition to antioxidant activity, resveratrol could inhibit platelet aggregation, and showed anticancer activity. The phenoxyl radicals of resveratrol produced during oxidation by hydroxyl radicals, one-electron oxidants, and peroxyl radicals showed absorption maximum at 410 nm (Fig. I). Reports indicate that trans-resveratrol is a better radical scavenger than vitamins E and C and its activity is similar to that of the flavonoids epicatechin and quercetin. From the comparison of the spectral and kinetic properties of the transients derived from trans-resveratrol and its analogues, it could be concluded that in the neutral and acidic solutions, the para-hydroxy... 

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