Synthesis, DNA/BSA binding studies and biological assay of nickel(II) complexes incorporating tridentate aroylhydrazone and triphenylphosphine ligands.

Two new nickel (II) triphenylphosphine complexes derived from tridentate aroylhydrazone ligands [HL = 2-hydroxy-3-methoxybenzylidene)benzohydrazone and HL = '-(2-hydroxy-3-methoxybenzylidene)-2-hydroxybenzoylhydrazone] and triphenylphosphine were prepared and their molecular structures were determined by single crystal X-ray diffraction analysis. Both nickel(II) complexes showed slightly distorted square planar geometry with one tridentate aroylhydrazone ligand coordinated through ONO donor atoms and one triphenylphosphine ligand coordinated to the nickel center through the phosphorus atom. DNA interaction studies indicated that both complexes possessed higher affinity to herring sperm DNA (HS-DNA) than the corresponding free aroylhydrazone ligand. Molecular docking investigations showed that both complexes could bind to DNA through intercalation of the phenyl rings between adjacent base pairs in the double helix. Meanwhile, bovine serum albumin (BSA) binding studies revealed the complexes could effectively interact with BSA and change the secondary structure of BSA. Further pharmacological evaluations of the synthesized complexes by antioxidant assays demonstrated high antioxidant activity against NO· and O˙ radicals. The anticancer activity of each complex was assessed through cytotoxicity assays (CCK-8 kit) toward A549 and MCF-7 cancer cell and normal L-02 cell lines. Significantly, the Ni(II) complex derived from HL ligand was found to be more effective cytotoxic toward MCF-7cancerous cell with the IC value equaled 9.7 μM, which showed potent cytotoxic activity over standard drug cisplatin.