Comparative study of polyphenol scavenging activities assessed by different methods

The effect of procyanidin solutions on superoxide anion radicals was studie d with an enzymatic method and their EC50 values were determined. A compara tive study of the results suggested that the free radical scavenger potenti al of these phenolic compounds closely depends on their chemical and stereo chemical structures. Oligomeric procyanidins were isolated in different fra ctions from grapes and wines by low- and high-pressure liquid chromatograph y. These compounds were found to be efficient free radical scavengers even for the weak concentrations in wines. Their activity in grapes or wines was much stronger than that of other commercially available natural antioxidan ts (such as ascorbic acid and gallic acid). The effect of tannins isolated from grapes on different radicals was analyzed according to three distinct methods: an enzymatic method for superoxide anion radicals (O-2(.-)), a che mical method for the stable 1,1-diphenyl-2-picrylhydrazyl radical (DPPH.), and an immunochemical method to study the scavenging activity of seed procy anidins on DNA lesions induced by the radical HO..