Binding studies of a novel antitumor palladium(II) complex to calf thymus DNA

The interaction of new 1, 10-phenanthrolineoctyldithiocarbamatopalladium (II) nitrate with DNA from calf thymus was investigated at 300 and 310 K in a Tris-HCl buffer of pH 7.0 medium containing 20 mM sodium chloride. This water soluble, square planar Pd(II) complex has been synthesized and spectroscopic (electronic, infrared, and nuclear magnetic resonance) and elemental analysis of the complex are discussed. This complex shows greater growth inhibitory activity against human tumor cell line K562 than cisplatin. Results of UV-visible studies show that the complex exhibits cooperative binding with DNA and denatures the DNA at an extremely low concentration (～11.98 μM). Fluorescence studies reveal that the mode of binding of this complex with DNA seems to be intercalation. The results of sephadex G-25 column show that the binding of metal complex with DNA is so strong that it does not readily break. Several binding and thermodynamic parameters are also described. They may shed light on the mechanisms of interaction of this agent with DNA, which should be quite different from that of cisplatin.