Trans-Pd/Pt(II) saccharinate complexes with a phosphine ligand: Synthesis, cytotoxicity and structure-activity relationship.

New trans-[Pd(sac)(PPhMe)(DMSO)]·HO (Pd) and trans-[Pt(sac)(PPhMe)]·HO (Pt) complexes (sac = saccharinate and PPhMe = dimethylphenylphosphine) were synthesized and characterized by elemental analysis, IR, NMR, ESI-MS spectral analyses and X-ray diffraction. The complexes were evaluated for their in vitro cytotoxicity against breast (MCF-7), colon (HCT116) and lung (A549) human cancer cell lines. The ATP viability assay displayed that Pd was biologically inactive, but Pt showed significant anticancer potency on MCF-7 cancer cells, similar to cisplatin. The results suggested that Pt targeted DNA, whereas Pd displayed higher binding affinity towards human serum albumin (HSA). Mechanism of action studies of Pt suggested apoptotic cell death due to significant increase in intracellular ROS (reactive oxygen species) levels, mitochondrial damage and formation of DNA double-strand breaks. Finally, this work represents a new example of potent transplatin anticancer complexes.