About Desferrioxamine Antidote, Natural product from Streptomyces pilosus, An iron-Chelating Agent, anti-oxidant. Mechanism of Action of Desferrioxamine Desferrioxamine is a chelating agent. The chelating agents being antagonists compete with body ligands for the heavy metals. They usually have 2 or more reacting groups which can hold the metal from 2 sides to form a ring. These should have higher affinity for the toxic metal to be excreted than Ca 2+ which is readily available in plasma than in body fluids. They should also have higher affinity for the metal than the body ligands. Desferrioxamine (3 hydroxy group) binds to ferric iron and preventing entering in to the further chemical reactions and forms water soluble iron complex and easily excreted in the urine and bile. It can also form chelating complex with aluminium and therefore used in the treatment of aluminium overload.