DNA binding and antitumor activities of zinc(II) complexes with some S-alkenyl derivatives of thiosalicylic acid

Two zinc(II) complexes with S-alkenyl derivatives of thiosalicylic acid as ligands have been synthesized and characterized by microanalysis, IR, H-1 and C-13 NMR spectroscopy. The complexes were obtained by direct reaction of ZnCl2 with S-alkenyl derivatives of thiosalicylic acid in aqueous solution. On the basis of the physico-chemical and spectroscopic data, we conclude that the ligands are bidentately coordinated to the zinc(II) center. The interaction of the complexes with calf thymus DNA (CT-DNA) has been investigated by absorption (UV-Vis) and ethidium bromide displacement studies. The cytotoxic activities of the complexes were evaluated in comparison with oxaliplatin and cisplatin against two different cancer cell lines: murine colon carcinoma (CT26) and mouse melanoma (B16F1), while non-cancerous mouse mesenchymal stem cells (mMSCs) were used as a control. Both complexes showed moderate activities against mouse colon cancer and melanoma cells. The decrease in viability of melanoma cells is caused by induction of apoptosis and G2 phase arrest. The zinc(II) complex with S-propenyl thiosalicylic acid, although has a significantly weaker cytotoxic effect on tumor cells than oxaliplatin and cisplatin, acts more selectively on tumor cells than the known drugs.