Spectrophotometric Study of Mithramycin Complexes with Cu(II), Fe(III) and Tb(III)

Abstract

The coordination of the anticancer drug mithramycin to Tb(III), Fe(II1) and Cu(II) was studied in aqueous solution using absorption measurements. The stability constants were calculated from equilibrium competition experiments by means of the SQUAD program. For both first ions. the compebtor was oxalic acid and for the latter the competitor was the Cu(II) ions. Cu(I1) at pH 7.5, Fe(II1) at pH 3.5 and Tb(II1) at pH 5.5 formed respectively 1:2, 1:3 and 1:4 metal-to-ligand species.