Novel approaches to prodrugs of anticancer diaminodichloroplatinum(II) complexes activated by stereoselective enzymatic ester hydrolysis.

A series of dichloro(ethylenediamine)-type platinum complexes bearing ester-, amide- and ether-bonded alkyl straight chains (C2-C18) was prepared as a model for the prodrug of cis-diamminedichloroplatinum (CDDP). Evaluation of cytotoxic activity of the complexes against the S-180 cell line proved that their enzymatic hydrolysis in the cells lowered the permeability to the cell membranes resulting in an increase of pharmacological activity. Optically active isomers of dichloro(N-2(2-phenylpropanoyloxy)ethyl)-2,3-diaminopropanamide )platinum(II) were prepared. They were re-activated stereoselectively, and a tenfold difference in activity was observed based on the differences in chiral discrimination by enzymes.