Binary mixtures of natural polyphenolic antioxidants with ascorbic acid: impact of interactions on the antiradical activity

Selected natural polyphenols, including ferulic acid (FA) and hesperetin (Hp) were tested for their antiradical activity using the stable radical DPPH^•, as a first step to rank them according to their potency. Ranking also included quercetin (Qt), a very well-studied natural, polyphenolic antioxidant, and ascorbic acid (AA). All phenolics considered were also tested in binary mixtures with AA, to illustrate possible mixture effects. By employing a simple linear regression approach, combinations of AA / Qt, AA / FA and AA / Hp were shown to result in antagonism. The results were discussed on the ground of regeneration reactions, based on the redox potentials.