A New Family of Sequence-Specific DNA-Cleaving Agents Directed by Triple-Helical Structures: Benzopyridoindole-EDTA Conjugates

DNA-Targeted Metallodrugs: An Untapped Source of Artificial Gene Editing Technology

DNA binding metal complexes are synonymous with anticancer drug discovery. Given the array of structural and chemical reactivity properties available through careful design, metal complexes have been directed to bind nucleic acid structures through covalent or noncovalent binding modes. Several recognition modes - including crosslinking, intercalation, and oxidation - are central to the clinical success of broad-spectrum anticancer metallodrugs. However, recent progress in nucleic acid click chemistry coupled with advancement in our understanding of metal complex-nucleic acid interactions has opened up new avenues in genetic engineering and targeted therapies. Several of these applications are enabled by the hybridisation of oligonucleotide or polyamine probes to discrete metal complexes, which facilitate site-specific reactivity at the nucleic acid interface under the guidance of the probe. This Review focuses on recent advancements in hybrid design and, by way of an introduction to this topic, we provide a detailed overview of nucleic acid structures and metal complex-nucleic acid interactions. Our aim is to provide readers with an insight on the rational design of metal complexes with DNA recognition properties and an understanding of how the sequence-specific targeting of these interactions can be achieved for gene engineering applications.

Photoenhanced oxidative DNA cleavage with non-heme iron(II) complexes

The DNA cleavage activity of iron(II) complexes of a series of monotopic pentadentate N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine (N4Py)-derived ligands (1-5) was investigated under laser irradiation at 473, 400.8, and 355 nm in the absence of a reducing agent and compared to that under ambient lighting. A significant increase in activity was observed under laser irradiation, which is dependent on the structural characteristics of the complexes and the wavelength and power of irradiation. Under photoirradiation at 355 nm, direct double-stand DNA cleavage activity was observed with Fe(II)-1 and Fe(II)-3-5, and a 56-fold increase in the single-strand cleavage activity was observed with Fe(II)-2. Mechanistic investigations revealed that O(2)(•-), (1)O(2), and OH(•) contribute to the photoenhanced DNA cleavage activity, and that their relative contribution is dependent on the wavelength. It is proposed that the origin of the increase in activity is the photoenhanced formation of an Fe(III)OOH intermediate as the active species or precursor.