Crystal structures, DNA interaction and antiproliferative activities of the cobalt(II) and zinc(II) complexes of 2-amino-1,3,4-thiadiazole with demethylcantharate

Two new mixed-ligand complexes [M(atdz)(DCA)(H2O)2]·2H2O, (M = Co(II), Zn(II); atdz = 2-amino-1,3,4-thiadiazole, C2H3N3S; DCA = demethylcantharate, 7-oxabicyclo[2,2,1]heptane-2,3-dicarboxylate, C8H8O5) were prepared and characterized by elemental analysis. The structures of the complexes were determined by X-ray diffraction. The crystals have empirical formulas CoC10H19N3O9S (1) and ZnC10H19N3O9S (2), respectively. Complex 1 and 2 are monoclinic systems with space group P21/m. The structures of the complexes assume severely distorted octahedral geometries. The DNA binding properties of the complexes were investigated by electronic absorption spectra, thermal denaturation studies, fluorescence quenching studies and viscosity measurements. All the results showed the interaction modes between the complexes and DNA were partial intercalation. The results of agarose gel electrophoresis indicated the complexes could cleave supercoiled DNA. The antiproliferative activities testing revealed that all the complexes showed weak to moderate activities against human hepatoma cells (SMMC7721) and human breast cells (MCF-7) in vitro.