In vitro and In vivo Studies of Potential Anticancer Agents of Platinum(II) Complexes of Dicyclopentadiene and Dithiocarbamates

Three platinum(II) complexes of dicyclopentadiene (DCP) and dithiocarbamates (DTC), namely, [Pt(η4-DCP)(Me2DTC)]PF6 (1), [Pt(η4-DCP)(Et2DTC)]PF6 (2) and [Pt(η4-DCP)(Bz2DTC)]PF6 (3) [Me2DTC = dimethyldithiocarbamate, Et2DTC = diethyldithiocarbamate, and Bz2DTC = dibenzyldithiocarbamate] were prepared and characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy. The spectroscopic data indicated the coordination of both DCP and dithiocarbamate ligands to platinum(II). The solution chemisty of complex 1 revealed that the complexes are stable in both DMSO and 1:1 mixture of DMSO: H2O. In vitro cytotoxicity of the complexes relative to cisplatin was tested using MTT assay, against CHL-1 (human melanoma cancer cells), MDA-MB-231 (breast cancer cells), A549 (lung cancer cells), and B16 (murine melanoma cancer cells). The antiproliferative effect of all three prepared complexes was found to be significantly higher than cisplatin. Furthermore, flow cytometric analysis of complex 1 showed that the complex induced apoptosis, oxidative stress, mitochondrial potential depolarization and cell cycle arrest in a concentration-dependent pattern in the CHL-1 cells. Confirmation of apoptosis via gene expression analysis demonstrated down-regulation of anti-apoptotic genes and up-regulation of pro-apoptotic genes in the CHL-1 cells. Wound healing assays also lent support to the strong cytotoxicity of the complexes. In vivo studies showed a significant reduction of tumor volume at the end of the experiment. In addition, the drug did not change the weight of the mice. In conclusion, complex 1 inhibited cell proliferation in vitro and reduced tumor growth in vivo.

Synthesis, cytotoxicity, induction of apoptosis, and interaction with DNA of dinuclear platinum(II) complexes

Six dicarboxylato-bridged dinuclear platinum(II) complexes S1-S6, with a newly designed chiral ligand, 2-{[(1R,2R)-2-aminocyclohexyl]amino}propanoic acid (HL), were prepared and spectrally characterized. The in vitro cytotoxicity of all resulting platinum(II) complexes was evaluated against human HCT-116, MCF-7, and HepG-2 tumor cell lines. The results show that all compounds exhibit positive biological activity toward HCT-116 and MCF-7 cell lines, of which complexes S3, S4, and S5, with succinate and its derivatives as bridges, showing better activity than the positive controls. Moreover, double-dyeing flow cytometric resection experiments indicate that the target compounds inhibit tumor cell growth by inducing apoptosis; gel electrophoresis experiments demonstrate the compounds' ability to prompt pET22b plasmid DNA degradation in almost the same way as oxaliplatin.