Synthesis, spectroscopic characterization and antiproliferative activity of two platinum(II) complexes containing N-donor heterocycles

Novel mononuclear complexes of Pt(II), cis-[PtCl2(DMSO)HL] 2DMSO (1), where HL = 7-amino-2-(methylthio)[ 1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylic acid and Pt(bdt)Cl2 (2), where bdt = [2,4-bis(5,6- diphenyl-1,2,4-triazin-3yl)-pyridine] have been synthesized and characterized by elemental analysis, IR and 1H NMR spectroscopy and X-ray crystallography diffraction analyses. The molecular structure of (1) shows that Pt(II) ion has a square planar geometry with N(3) bonded heterocycle ligand, two cis chloride anions and S-bonded dimethylsulfoxide. The antiproliferative activity of complexes (1) and (2) has been tested in vitro against HepG2 human hepatoma cells and non-malignant human-derived hepatic cells (Chang). Complex (1), cis-[PtCl2(DMSO)HL] 2DMSO, was effective inducer of apoptotic death on HepG2 cells and its cytotoxic activity was higher than that exerted by cisplatin. Apoptosis effect was associated with externalization of plasma membrane phosphatidylserine.