Cytotoxicity and DNA-binding property of water-soluble naphthalene diimide derivatives bearing 2-oligoethoxy ethanamine side chain end-labeled with tertiary amino groups

A series of novel water-soluble tri-substituted naphthalene diimide (NDI) derivatives bearing 2-oligoethoxy ethanamine side chain end-labeled with tertiary amino groups have been designed and synthesized. The cytotoxicity of the novel naphthalene diimides against cancer cell lines (K562, A549 and HeLa) showed that these compounds had excellent anti-cancer activity and the short length of the side chain (having one oxyethylene) was found to be beneficial to the observed anti-proliferative activity. Their DNA-binding properties were also studied using UV–Vis spectroscopy, fluorescence spectroscopy, and circular dichroism. The results showed that such tri-substituted NDI as DNA intercalators exhibited strong π–π stack binding capability and high binding affinities towards calf thymus (Ct) DNA and G-quadruplex (G4) DNA. The order of the binding constants is Ct-DNA > G4 DNA, which suggested that these compounds are more effective ligands to the duplex DNA. Graphical Abstract A series of novel water-soluble tri-substituted NDI derivatives bearing 2-oligoethoxy ethanamine side chains end-labeled with tertiary amino groups have been designed and synthesized. These compounds had excellent anti-cancer activity and the short length of the side chain (having one oxyethylene) would be beneficial to their anti-proliferative activity.