DNA binding, cytotoxicity and DNA cleavage promoted by gold(III) complexes

Square planar Au(III) complexes of 2,2′-dipyridylamine (A1), di(2-pyridyl)ketone (A2), 2-(4-chlorophenyl)-1H-imidazo[4,5-f] [1,10] phenanthroline (A3) and 2-(4-bromophenyl)-1H-imidazo[4,5-f][1,10] phenanthroline (A4) of type [Au(An)Cl2].Cl were synthesized and characterized using conductivity measurement, C,H,N elemental analysis, FT-IR, LC–MS, 1H and 13C NMR spectroscopy. The compounds manifested significant cytotoxic properties in vitro for brine shrimp lethality bioassay. The metal complexes were screened for series of DNA binding activity using UV–vis. absorption titration, hydrodynamic measurement and thermal DNA denaturation study. The nucleolytic activity was performed on plasmid pUC19 DNA. The Michaelis–Menten kinetic studies were performed to evaluate rate of enhancement in metal complexes mediated DNA cleavage over the noncatalyzed DNA cleavage.