[Dependence of biological activity of triamine type platinum (II) complexes on their composition and structure]

The growth-inhibiting effect on the roots of maize and cucumber shoots was studied. We tested 53 triamine complexes of platinum (cis*- and trans*-[Pt(NH3)*2LCl]Cl, cis*- and trans*-[PtHx*2LCl]Cl and [PtenLCl]Cl, where Hx is hydroxylamine, en is ethylenediamine, and L are various heterocycles, which either have biological activity and occur in the cells or have no biological activity and are foreign to the cells). The cis*-[Pt(NH3)*2LCl]Cl and [PtenLCl]Cl complexes showed cytostatic properties, and the latter were effective at higher concentrations. Small changes in the composition of ligand L led to marked changes in the biological activity of the complexes. In order to characterize the effect of the complexes, we first determined the time of development of the lateral root from its initial appearance to its divergence from the main root (Tlat). The complexes with cytostatic properties markedly inhibited root branching and increased Tlat. The other complexes had virtually no effect on Tlat and reduced the zone of lateral roots only at the expense of inhibition of the main root growth. The complexes with cytostatic properties markedly inhibited the main root growth with time. Parallel studies conducted in the Oncological Research Center, Russian Academy of Medical Sciences have shown that the complexes with cytostatic properties display distinct antitumor activity.