Improved selectivity of ZnNa3DTPA vs. Na5DTPA to abstract Cd2+ from plasma proteinsin vitro

Abstract

Since no chelating agent has been clinically approved for the treatment of Cd²⁺ intoxicated humans, we have previously investigated diethylenetriaminepentaacetic acid (Na₅DTPA) to abstract this toxic metal from plasma proteins in vitro. In addition to the complete mobilization of Cd²⁺, an inadvertent abstraction of Zn²⁺ from metalloproteins was also observed. Therefore, we have evaluated the effect of ZnNa₃DTPA on the plasma distribution of Ca, Cd, Cu, Fe and Zn after its addition to Cd²⁺-spiked rabbit plasma. ZnNa₃DTPA was as efficient as Na₅DTPA in abstracting Cd²⁺ (100% removal), but it did not abstract Zn²⁺. Thus, complexes between essential metals (e.g. Zn²⁺) and known chelating agents emerge as feasible candidates to decrease potential adverse side effects in patients.