Aliphatic polyamine ruthenium(II) complexes: crystal structure, DNA-binding, photocleavage, cytotoxicity, and antioxidation

2015-11-26T22:06:54Z (GMT) by Xian-Lan Hong Wen-Guan Lu
<div><p>The DNA-binding behaviors of two aliphatic polyamine Ru(II) complexes, [Ru(dppt)(dien)](ClO<sub>4</sub>)<sub>2</sub> (<b>1</b>) and [Ru(pta)(dien)](ClO<sub>4</sub>)<sub>2</sub> (<b>2</b>) (dppt, pta, and dien standing for 3-(1,10-phenanthrolin-2-yl)-5,6-diphenyl-as-triazine, 3-(1,10-phenanthrolin-2-yl)-5,6-diphenyl-as-triazino[5,6-f]-acenaphthylene, and diethylenetriamine, respectively), were studied through absorption titration, thermal denaturation, and viscosity measurements. The results indicate that the DNA-binding affinity of <b>2</b> is much greater than that of <b>1</b>; <b>2</b> binds to CT-DNA in an intercalative mode but <b>1</b> binds to CT-DNA through partial intercalation. In addition, the complexes react with DNA in an energy-driven process with a decrease in entropy. The photocleavage of plasmid pBR322 can be triggered by <b>1</b> and <b>2</b> and strengthened with an increased concentration of both complexes. The scavenging activity of <b>1</b> against hydroxyl radical (˙OH) is slightly better than that of <b>2</b> according to the antioxidation experiment. The standard cytotoxicity experiments were carried out with MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide); the results indicate that the proliferation of Hela, A549, and 7402 cells is inhibited by these two compounds in a dose-dependent manner. The X-ray crystal structure of <b>1</b> and some results of DFT (the density functional theory) calculations were analyzed to further understand the differences in DNA-binding strength of the complexes.</p></div>