Synthesis, characterization and biological activity of platinum(II) complexes with L- and D-ornithine ligands

Described herein is the synthesis of two platinum(II) complexes containing L-ornithine (1) or D-ornithine (2) as a ligand. The complexes were obtained by the direct reaction of aqueous solutions of potassium tetrachloroplatinate and L- or D-ornithine. The single crystal structures of 1 and 2 were determined and indicated that the Pt core is surrounded by an almost regular square planar coordination environment. The two complexes were thoroughly characterized by means of FT-IR, FT-Raman and NMR techniques. Furthermore, their ability to inhibit proliferation of human tumor cell lines was tested and the results indicate that 1 and 2 exert different cytotoxic effects. Particularly, the complex with the D-isomer of ornithine (2) showed a significantly greater cytotoxicity than that with the L-isomer (1). Finally, circular dichroism analysis indicated that 1 and 2 interact with DNA in a manner similar to that of cisplatin.