[A new property of aspirin and other salicylates. Their capacity for radical generation at the expense of chelating-oxidizing action on iron cations].

It was demonstrated that salicylic acid, by binding ions of ferrous iron, induces its oxidation to the oxide form by molecular oxygen with generation of active forms of oxygen. Salicylic acid may therefore form stable ferrosalicylic complexes only with iron oxide, in which case the affinity of salicylic acid for iron oxide is higher than that of o-phenanthroline and lower than that of EDTA. In the presence of ascorbate in the system with salicylic acid and iron ions continuous radical formation may take place due to alternating cycles of oxidation-reduction iron ions through the combined effect of salicylic acid and ascorbate on them. The initial salicylic acid content in commercial aspirin preparations and its intensive formation at pH values close to the physiological parameters were determined by colorimetry and the inner standard method. After incubation of aspirin preparations at pH close to the physiological values, accelerated oxidation of ferrous iron with formation of active oxygen forms was recorded, which was evidently due to salicylic acid produced as the result of aspirin breakdown under such conditions.