Synthesis, characterization, DNA binding, and cytotoxic studies of some mixed-ligand palladium(II) and platinum(II) complexes of alpha-diimine and amino acids

The syntheses of nine palladium(II) complexes of type [Pd(phen)(AA)]+ (where AA is an anion of glycine, L-alanine, L-leucine, L-phenylalanine, L-tyrosine, L-tryptophan, L-valine, L-proline, or L-serine) have been achieved. These palladium(II) complexes have been characterized by ultraviolet-visible, infrared, and 1H NMR spectroscopy. The binding studies of several complexes [M(NN)(AA)]+ (where M is Pd(II) as Pt(II), NN is 2,2'-bipyridine or 1,10-phenanthrodine, and AA is an anion of amino acid) with calf thymus DNA have been carried out using UV difference absorption and fluorescence spectroscopy. The mode of binding of the above complexes to DNA suggests the involvement of the hydrogen bonding between them. Several complexes [M(phen)(AA)]+ (where M is Pd(II) or Pt(II) and AA is an anion of amino acid) have also been screened for cytotoxicity in P388 lymphocytic cells. Of them, only two complexes, [Pd(Phen)(Gly)]+ and [Pd(phen)(Val)]+, show comparable cytotoxicity, as cisplatin does.