FERROUS ION FORMATION BY FERRIOXAMINE PREPARED FROM AGED DESFERRIOXAMINE - A POTENTIAL PROOXIDANT PROPERTY

The siderophore desferrioxamine (DEFOM) binds ferric ions in a 1:1 rat io resulting in a ferrioxamine (FOM) complex. When DEFOM is stored or heat degraded, the resulting FOMD undergoes an autoreduction with the transfer of electrons to the bound ferric ions forming ferrous ions, w hich react with Ferrozine to yield a pink-coloured complex absorbing a t 562 nm. Heat-aged DEFOM forms a FOMD complex is placed in a phosphat e buffer at pH 7.4, ferrous ions autoxidise transferring electrons to molecular oxygen to form superoxide and hydrogen peroxide. Fenton chem istry leading to the formation of hydroxyl radicals can then occur. St udies with a variety of reactive oxygen scavengers support a role for the hydroxyl radical in damage to the detector molecule deoxyribose. H owever, when EDTA is present, damage to deoxyribose is decreased and t he radicals causing deoxyribose degradation no longer appear to be cha racteristic of the hydroxyl radical.