A new nickel(II) complex with the thiosemicarbazone of quinoline-2-carboxaldehyde: structure, DNA-binding, cleavage, and cytotoxic activities

Abstract

[Ni(QTS)₂] · Cl · CH₃OH, where QST = quinoline-2-carboxaldehyde thiosemicarbazone, has been synthesized and characterized. The complex crystallized in a monoclinic system with space group P2(1)/n. Nickel(II) is situated in a distorted octahedral geometry with two tridentate ligands and one ligand is mono-deprotonated to coordinate to nickel(II). Interaction of the nickel(II) complex with calf thymus DNA was investigated by electronic absorption, CD, and fluorescence spectra. The results suggest that nickel(II) complex binds to DNA through a groove binding mode. The nickel(II) complex exhibited efficient DNA cleavage at micromolar concentration in the presence of ascorbate with hydroxyl radicals as the active species. In vitro cytotoxicity assay showed that the nickel(II) complex was more potent against MCF-7 cell line but less active against A-549 cell line than cisplatin at the concentrations tested.

Keywords:

• Nickel complex
• Thiosemicarbazone
• DNA-binding
• DNA cleavage
• Cytotoxicity

Acknowledgments

Prof. Guo Zijian (Nanjing University) and Prof. Tan Lifeng (Xiangtan University) are gratefully acknowledged for providing the laboratory facilities. Dr Wang Xiaoyong is gratefully acknowledged for the technical assistance and helpful suggestions.