Toward overcoming cisplatin resistance via sterically hindered platinum(II) complexes.

A number of platinum(II) complexes with steric hindrance derived from (1R,2R)-N(1)-benzylcyclohexane-1,2-diamine derivatives were designed and prepared. Biological assay indicated that most complexes showed antitumor activity against the tested cancer cell lines, especially those with chloride anions as leaving groups had compatible or superior activity to cisplatin and oxaliplatin. Complex 2a, as the most potent agent, is also sensitive to cisplatin resistant SGC7901/CDDP cancer cell line, which has been subsequently studied by cellular uptake, flow cytometry, gel electrophoresis and western blot assays. The steric hindrance resulting from a pending 2-fluorobenzyl moiety of the ligand might be the key factor for its ability to overcome cisplatin resistant cancer cells.