The effect of ancillary ligand chirality and phenanthroline functional group substitution on the cytotoxicity of platinum(II)-based metallointercalators.

Fifteen platinum(II)-based metallointercalators have been synthesised that utilise substituted 1,10-phenanthroline (phen) ligands, including 5-chloro-1,10-phenanthroline (5-Cl-phen), 5-methyl-1,10-phenanthroline (5-CH3-phen), 5-amino-1,10-phenanthroline (5-NH2-phen), 5-nitro-1,10-phenanthroline (5-NO2-phen) and dipyrido[3,2-d:2',3'-f]quinoxaline (dpq), and achiral ethylenediamine (en) and the chiral ancillary ligands 1S,2S-diaminocyclohexane (S,S-dach) and 1R,2R-diaminocyclohexane (R,R-dach). Their cytotoxicity in the L1210 murine leukaemia cell line was determined using growth inhibition assays. The most cytotoxic metal complexes are those that contain S,S-dach ancillary ligands and 5-CH3-phen intercalating ligands.