Synthesis, characterization and anti-cancer studies of Mn(II), Cu(II), Zn(II) and Pt(II) dithiocarbamate complexes - crystal structures of the Cu(II) and Pt (II) complexes

Mn(II), Cu(II), Zn(II) and Pt(II) complexes of 2-((p-tolylamino)methyl)phenolyldithiocarbamate were synthesized and characterized by elemental analyses and spectroscopic techniques. Spectroscopic studies indicate four coordinate geometry around the metal(II) ions and single crystal X-ray crystallography confirmed the molecular structures of Cu(II) and Pt(II) complexes as distorted square planar. In vitro cytotoxic effects of the complexes, indicative of potential anti-cancer properties, were evaluated using human cancer cell lines HeLa and MRC5-SV2, and a normal cell line, MRC5. The complexes exhibited significant toxicity against the cancer cell lines, with IC50 values of less than 50 mu M after 48 h of exposure. Cu(II) and Zn(II) were the most potent and were virtually equipotent in their cytotoxicity against each of the two cancer cells, but only Zn(II) exhibited higher selectivity for a cancer cell than for a normal cell. Mn(II) complex was the least potent, while Pt(II) was the least cancer cell-selective, exhibiting significantly higher toxicity against the parental (normal) MRC-5 cell than against its cancer variant, MRC5-SV2. These compounds could, therefore, inspire the development of inorganic drug leads to generate novel anti-cancer drugs to be delivered directly to the cancerous tissue or through special delivery systems.