DNA interaction and anticancer evaluation of new zinc(II), ruthenium(II), rhodium(III), palladium(II), silver(I) and platinum(II) complexes based on kojic acid; X-ray crystal structure of [Ag(ka)(PPh3)]·H2O

Abstract

The syntheses of some new zinc(II), palladium(II), platinum(II), ruthenium(II), rhodium(III) and silver(I) complexes of kojic acid (Hka) in both the absence and the presence of N,N- (2,2′-bipyridyl) and P- (triphenylphosphine) ligands are reported. The X-ray crystal structure of the mixed-ligand complex, [Ag(ka)(PPh3)], has been determined. It has been crystallized in a monoclinic lattice with space group symmetry P21/n. The molecular structures of the complexes are discussed on the basis of their IR, NMR (1H, 13C, 31P), UV-Vis, and EI and maldi-mass spectra, elemental analyses, molar conductivities and TGA behaviour. Kojic acid coordinates to the central metal ions in a mono-negative bidentate fashion through the carbonyl O- and the deprotonated ring hydroxy-O atoms. The in vitro anticancer activities of several of the complexes have been examined against the human ovarian cancer (VC-8-BRCA & VC-8) cell lines. The IC50 values for cell growth proliferation of [Ag(ka)(PPh3)] are 8.80 and 8.87 μM, respectively. The corresponding IC50 values for cisplatin are 9.12 and 10.07 μM. The DNA-binding properties of some of the complexes have been studied using UV-vis spectroscopy. The results indicate that the complexes may undergo intercalative CT-DNA binding in view of their hypochromism. The binding constants (Kb) of the complexes with CT-DNA show low-to-moderate binding abilities, which may result from steric hindrance around the metal ions from the primary chelate (Hka) or the bulky secondary (bpy, PPh3) moieties.