Stabilities of Metal Complexes of Mugineic Acids and Their Specific Affinities for Iron(III)

Equilibria between several metal ions and mugineic acids, phytosiderophores in gramineous plants, were potentiometrically investigated in aqueous solutions and the stabilities of the complex species formed were determined. Only iron(III) formed very stable species with the quadrivalent anions of mugineic acids, and their stability constants were estimated to be 1032.5∼1033.3.