Anticancer and DNA Interaction of New Zinc(II), Palladium(II), Platinum(II) and Silver(I) Complexes Based on Indol-3-Acetic Acid; Solid and Solution Studies

The syntheses of new zinc(II), palladium(II), platinum(II) and silver(I) complexes of indol-3-acetic acid (HIAA) as a primary chelate and N,N- (2,2'-bipyridyl; bpy) or P- (triphenylphosphine; PPh3) as secondary chelate are reported. The molecular structures of these complexes are discussed based on spectral {IR, NMR (H-1, C-13, P-31), UV-Vis, and EI and maldi-mass}, elemental analysis, molar conductivity and TGA measurements. HIAA coordinates the metal ions through the two O-atoms of -COO-, deprotonated O = C-O- or carbonyl O-atom (HO-C = O) in a mononegative bidentate, mononegative monodentate or neutral monodentate fashion, respectively. In case of the binuclear Ag(I) complex, HIAA behaves as mononegative bidentate ligand, binding two Ag(I) ions through both carbonyl O- and deprotonated -O- atoms. The dissociation constant (pK(a)) of HIAA was determined and the stoichiometry of the complexes in solution was established using the molar ratio and Job's methods. The anticancer activity of some of the complexes was examined against the human ovarian cancer (VC-8-BRCA and VC-8) cell lines. The DNA-binding properties of the water-soluble complexes were investigated using UV-vis spectroscopy. The complexes may undergo intercalative CT-DNA binding in view of their hypochromism. The binding constants (K-b ) of the complexes with CT-DNA show high-to-moderate binding abilities.