Fe(ii)–EDTA chelate-induced aromatic hydroxylation of terephthalate as a new method for the evaluation of hydroxyl radical-scavenging ability

Abstract

The investigation of Fe(II)–EDTA chelate-induced aromatic hydroxylation of terephthalate in pH 7.4 phosphate buffer solution and a new method for the evaluation of hydroxyl radical-scavenging ability are reported. The method is based on attack of the hydroxyl radical on the terephthalate to produce highly fluorescent 2-hydroxyterephthalate, which is detected fluorimetrically. The formation of hydroxyl radical is believed to be the result of the reduction of molecular oxygen by Fe(II)–EDTA to form superoxide radical, which in turn dismutates to hydrogen peroxide, and then Fe(II)–EDTA catalyzes the decomposition of hydrogen peroxide to produce hydroxyl radical. The mechanism of the generation of hydroxyl radical in the proposed system was confirmed. This study established a simple and inexpensive method for the evaluation of the scavenging ability of some compounds on hydroxyl radicals.