Platinum complexes of diaminocarboxylates and their ethyl ester derivatives: Antitumor activity and interaction with deoxyribonucleic acid.

Abstract
The Pt complexes of diaminocarboxylates (charged complexes) and their ethyl ester derivatives (non-charged complexes) were prepared and examined for antitumor activity [in mice with L-1210 and P-388 leukemia]. The non-charged complexes are antitumor-active, while the charged complexes are inactive. The interaction of calf thymus DNA with the charged and non-charged complexes was examined by UV difference spectroscopy. Since the UV difference spectral patterns obtained in this work were almost the same, the binding mode of the charged complexes to DNA seems to be the same as that of the non-charged complexes. The presence of negative charge lowers the reactivity of the Pt complexes with DNA. The antitumor-inactivity of the charged complexes may be due to a combination of their reduced ability to permeate into cells and the lower reactivity with DNA.