Interactions of terpyridines and their Pt(II) complexes with G-quadruplex DNAs and telomerase inhibition

Three terpyridine derivatives L1-L3 and their Pt(II) complexes 1-3 have been prepared, the binding interactions with human telomeric (h-telo) and the promoter c-kit2 and c-myc G-quadruplex DNAs were investigated. All the ligands and the complexes are potent stabilisers of the G-quadruplex structures and exhibit the G-quadruplex selectivity over duplex. The binding affinities of these compounds to G-quadruplexes are higher than to calf thymus DNA. Three Pt(II) complexes are also potent telomerase inhibitors. CD spectra show that both the ligands and the complexes can induce the formation of anti-parallel G-quadruplex structure of h-telo in the absence and presence of K(+). Each h-telo G-quadruplex binds two ligand or complex molecules using Job plot analysis.