[Ru(L)2(3-tppp)]2 + (L = bpy, phen) stabilizes two different forms of the human telomeric G-quadruplex DNA

• Two new [Ru(L)2(3-tppp)]2 + complexes have been synthesized and characterized.
• The interaction of the title complex with two different forms of the human telomeric G-quadruplexes DNA was explored.
• The present investigation led to the identification of potent G-quadruplex stabilizers with high selectivity over duplex DNA.
• Both complexes show preference for mixed-hybrid G-quadruplex over antiparallel G-quadruplex.

The binding properties of new complexes [Ru(L)2(3-tppp)]2 + (L = bpy, phen) towards two different forms of the human telomeric G-quadruplexes DNA have been investigated by UV–Vis spectroscopy, fluorescent indicator displacement (FID) assays, fluorescence resonance energy transfer (FRET) melting assays and molecular docking studies. The molecular docking studies indicated that both complexes interacted with 22AG with the stoichiometric ratio of 1:1, but the two complexes showed different G-quadruplexed DNA binding affinity. Complex 2 bound to the G-quadruplexes DNA more tightly than complex 1 did. Moreover, the FRET melting assay revealed that both complexes could be potential stabilizers for G-quadruplex architectures. These studies are useful not only for better understanding of the interaction between the target G-quadruplexes DNA and metal complexes but also valuable in defining the best strategy to prepare metal complexes as potential anticancer drugs.

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