Transition metal complexes with a novel guanine-based (E)-2-(2-(pyridin-2-ylmethylene)hydrazinyl)quinazolin-4(3H)-one: Synthesis, characterization, interaction with DNA and albumins and antioxidant activity

A novel guanine-inspired 2-hydrazinyl-4(3H)-quinazolinone derivative (HL) has been synthesized and characterized. The reaction of HL with Cu(II) in a 1:1 M:L ratio and with Cu(II), Ni(II) and Zn(II) in a 1:2 M:L ratio resulted in the formation of complexes, [Cu(L)(H2O)(2)](NO3), 1 and [M(L)(2)] (M = Cu for 2, Ni for 3 and Zn for 4), respectively. In all these complexes, the ligand L is tridentately bound to the corresponding metal. The affinity of the complexes for calf-thymus DNA was examined by diverse techniques and the complexes can intercalate between the DNA-bases. The cleavage ability of the complexes towards supercoiled circular pBR322 plasmid DNA was examined via agarose gel electrophoresis experiments in the absence or presence of UVA, UVB or visible light and the DNA-cleavage was found to depend on the concentration and light wavelength used. The binding of the complexes for bovine and human serum albumins was also investigated in order to determine the binding constants and the binding subdomain. The scavenging activity of the compounds was evaluated towards free radicals 1,1-diphenyl-picrylhydrazyl and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid).