Synthesis, crystal structure, DNA cleavage and antitumor activity of two copper(II) complexes with N-sulfonamide ligand

Two Cu(II) complexes, [Cu(L1)(2)(py)(2)(H2O] (C1) (HL1 = N-(5-(4-methylphenyl)-[1,3,4]-thiadiazole-2-yl)-naphtalenesulfonamide) and [Cu(HL2)(4)](OH)(2) (C2) (HL2 = N-(5-(4-methoxyphenyl)-[1,3,4]-thiadiazole-2-yl)-toluenesulfonamide) with two new obtained ligands were synthesized. The X-ray crystal structures of the complexes have been determined. In the complex C1, the Cu(II) ion is five-coordinated, forming a CuN4O chromophore and in the complex C2, the Cu(II) ion is four-coordinated, forming a CuN4 chromophore. The ligands act as monodentate, coordinating the metal ion through a single N-thiadiazole atom. For the complex C1, the molecules from the reaction medium (pyridine and water) are also involved in the coordination of the Cu(II) ion. The complexes have a slightly distorted square pyramidal square-planar (C1) and a square-planar (C2) geometry. The compounds were characterized by FT-IR, electronic, EPR spectroscopic and magnetic methods. The nuclease activity studies of the synthesized complexes confirm their capacity to cleavage the DNA molecule. The results of in vitro cell cytotoxicity on three carcinoma cell lines (HeLa, A2780 and A2780cisR) are in concordance with the DNA cleavage study and with the SOD-mimetic activity and indicate that both complexes have antitumor activity. The antitumor activity was compared with Cisplatin and C1 complex demonstrated a higher activity. Both complexes overcame the Cisplatin resistance tence in A2789cisR cells whitout enhanced toxicity on normal fibroblastic cells.