Cytotoxicity and DNA interaction in a series of aryl terminated iminopyridine Pt(II) complexes

A series of iminopyridine complexes of platinum(II), bearing a flexible diethereal, aryl terminated residue, where the size of aryl group is varied from phenyl to 9-anthracenyl, was synthesized. The new complexes are soluble and stable in DMSO/H2O mixtures. Besides the metal center, aryl groups are available for further interactions with DNA, due to the good side chain flexibility. The new aryl functionalized iminopyridine dichlorido platinum(II) complexes show a significant antiproliferative activity on ovarian carcinoma cells and notably, complex 13 is able to overcome cisplatin resistance. The study of the interaction mode of 13 with DNA highlighted the ability to form a molecular complex characterized by a dual (intercalative and groove binding) geometry. The complex is also able to covalently add to DNA even though interstrand cross-links appear significantly hampered with respect to cisplatin. The interactions with the macromolecule are discussed in view of the observed cell effect.