Biologically Active Cu(II), Co(II), Ni(II) and Zn(II) Complexes of Pyrimidine Derivative Schiff Base: DNA Binding, Antioxidant, Antibacterial and In Vitro Anticancer Studies

A new pyrimidine derivative Schiff base ligand (HL) [HL = 2-(4,6-dimethylpyrimidin-2-ylimino)methyl)-4-nitrophenol] and its metal(II) complexes [CuL2] (1), [CoL2] (2), [NiL2] (3) and [ZnL2] (4) have been synthesized and characterized by several spectral techniques. The square planar geometry of the complexes 1-4 confirmed by UV-Visible, ESR and EI-mass spectral techniques. DNA binding study of the complexes 1-4 with Calf Thymus (CT) DNA using absorption spectral titration at different pH (4.0, 7.0 & 10.0) have been scrutinized that the complexes 1-4 bound by groove binding mode with significant binding constant values (K (b) = 5.61 x 10(5) M-1 (1), 2.60 x 10(5) M-1 (2), 2.48 x 10(5) M-1 (3) and 6.98 x 10(4) M-1 (4) at pH = 10.0. Binding nature of the complexes 1-4 with CT DNA has further confirmed by emission, viscometry and cyclic voltammetry which also recommended that complexes 1-4 bound with CT DNA. The complexes 1-4 possessed effective scavenging effect during the DPPH and SOD radical scavenging method. The antibacterial activity of the complexes 1-4 was vetted against several bacterial strains and the results shows that the ligand (HL) and complexes 1-4 are more active in Bascillus subtilis. The anticancer activity of the complexes 1-4 was evaluated against Human Breast Cancer Cells (MCF-7), Human Cervical Cancer Cells (HeLa), Human Laryngeal Epithelial Carcinoma (HEp2) and Normal Human Dermal Fibroblast (NHDF) by MTT assay, which revealed that complexes 1 & 2 have modest activity against the cancer cell lines than ligand (HL) and complexes 3 & 4.