DNA cleavage by the Cu(ii) complex of the DNA-intercalating 9-bis(pyridin-2-ylmethyl)aminobenzo[b]quinolizinium

Abstract

The synthesis and the investigation of the Cu(II)-binding, the DNA-binding, and the DNA-damaging properties of a conjugate between the benzo[b]quinolizinium ion and the bis(pyridin-2-ylmethyl)amino receptor are presented. Photometric and fluorimetric titrations as well as CD spectroscopic analysis reveal that the 9-bis(pyridin-2-ylmethyl)aminobenzo[b]quinolizinium ligand intercalates into DNA (K_b = 1.9 × 10⁴ M⁻¹) and exhibits a high selectivity towards complexation of Cu²⁺ in water (K_b = 4.3 × 10⁴ M⁻¹). This combination of functionalities allows to localize Cu²⁺ in close proximity of DNA, where these metal ions induce efficient DNA damage, as shown by the single-strand cleavage of supercoiled plasmid DNA. Notably, the DNA cleavage does not require additional reagents nor light.