Acetic acid, ethylenediamine tetra formation

Iron should be coordinated by the chelate in such a manner as to prevent direct access of oxygen and hydrogen peroxide. If this is achieved, then hydroxyl-radical production will be reduced to a minimum. Some iron complexes, for instance ethylenediamine tetra-acetic acid (EDTA) (Fig. 3a), generate hydroxyl radicals efficiently while others such as DFO and the hydroxypyridinones (Fig. 3b) do not. By designing chelators that produce extremely stable complexes, the generation of hydroxyl radicals is further minimized. Such stable complex formation would also reduce the tendency for iron redistribution within the body. 

Complex formation reactions, in which the reactants are combined to form a soluble ion or compound. The most important reagent for formation of such complexes is ethylenediamine tetra-acetic acid, EDTA (as the disodium salt). 

The formation of hydroxyl radicals (HO ) by the reaction of the Cu(II) complex of ethylenediamine tetra-acetic acid (EDTA) with H2O2 in the presence of biological reductants, such as L-ascorbic acid and l-cysteine, has been demonstrated by ESR spectroscopy using water-soluble spin-traps (Ozawa et al. 1992). 

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