The iron-H2O2-iodide cytotoxic system

A potent antimicrobial system is described which consists of ferrous sulfate (Fe2+), hydrogen peroxide (H2O2), and iodide in 0.02 M sodium acetate buffer pH 5.5. H2O2 could be replaced by the H2O2-generating system glucose + glucose oxidase. This system, unlike the myeloperoxidase-H2O2-halide system, was ineffective when iodide was replaced by bromide, chloride, or thyroxine, and was inhibited by EDTA, the hydroxyl radical scavengers mannitol and ethanol, and phosphate and lactate buffers at the same concentration and pH as the acetate buffer used. The acetate buffer, however, could be replaced by water. It is proposed that Fe2+ and H2O2 (Fenton's reagent) generate OH X (or a closely related substance), which interacts with iodide to form one or more toxic species.