A series of mono- and bi-metallic metal complexes (with CuII, PtII and ZnII) with substituted polypyridyl
ligands have been prepared and their binding affinities towards quadruplex (c-Myc and human telomeric)
and duplex DNA (ds26 and calf thymus) determined using fluorescent indicator displacement (FID) assays
and UV/vis spectroscopic titrations. These studies have shown that the number of aromatic rings and
number/position of cyclic amine substituents on the ligands, play an important role in defining the DNA
binding abilities of the resulting metal complexes. We also show that bi-metallic complexes prepared
using a novel terpyridine-cyclen ligand have higher affinity towards G-quadruplex DNA as compared to
their mono-metallic counterparts. Cytotoxicity assays were carried out for all the new complexes against
an osteosarcoma cancer cell line (U2OS) as well as a normal fibroblast cell line (GM05757). Several of
these compounds displayed cytotoxicity similar to that of cisplatin.