Studies on the effect of metal ions of hydrazone complexes on interaction with nucleic acids, bovine serum albumin and antioxidant properties

Three new transition metal complexes of the type ML2 (where M = Ni(II), Co(II) or Cu(II); HL = N′-[phenyl(pyridin-2-yl)methylidene]furan-2-carbohydrazide]) have been prepared by treating [NiCl2(PPh3)2], [CoCl2(PPh3)2] or [CuCl2(PPh3)2] with N′-[phenyl(pyridin-2-yl)methylidene]furan-2-carbohydrazide derived from furoic acid hydrazide and 2-benzoyl pyridine wherein the hydrazone ligand (L) coordinated to the respective metal ions in 1:2 stoichiometry to mononuclear octahedral complex. The crystal structure of the complexes [NiL2] (1), [CoL2] (2) and [CuL2] (3) solved using single crystals revealed a distorted octahedral geometry around the metal ion involving the coordination of an azomethine nitrogen, a pyridine nitrogen and an enolic oxygen derived from deprotonation of the ligand. From the bioinorganic application point of view, a detailed work on the binding of the complexes 1, 2 and 3 with CT DNA as well as BSA was undertaken along with DNA cleavage. In vitro assay on the antioxidant activity of the above complexes and hydrazone ligand revealed that they possess significant antioxidant activity. However, among the newly synthesized hydrazone complexes, complex 3 having coordinated Cu2+ ion in its molecular structure exhibited superior activity in all the biological studies in comparison with the other two complexes possessing nickel and cobalt ions with same ligand (L).