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

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 fluorimetrical ly. The formation of hydroxyl radical is believed to be the result of the r eduction of molecular oxygen by Fe(ii)-EDTA to form superoxide radical, whi ch in turn dismutates to hydrogen peroxide, and then Fe(ii)-EDTA catalyzes the decomposition of hydrogen peroxide to produce hydroxyl radical. The mec hanism of the generation of hydroxyl radical in the proposed system was con firmed. This study established a simple and inexpensive method for the eval uation of the scavenging ability of some compounds on hydroxyl radicals.