Metallo-Organic G-Quadruplex Ligands in Anticancer Drug Design

Guanine-rich DNA sequences can form planar four-stranded structures via Hoogsteen hydrogen bonds. These sequences in telomeric DNA and some oncogenes have been identified as targets for novel anticancer drugs. Consequently, there is great current interest in developing small molecules that can facilitate the formation of, and stabilize G-quadruplexes as potent antitumor chemotherapeutic agents. Metal complexes with planar geometries and π-delocalised ligands are emerging as a new class of quadruplex DNA ligand with unique features for optimal binding. This review will summarize the different types of metal-based compounds that target G-quadruplexes and provide useful information on the design of small ligands.