DNA-binding and anti-oxidation properties of binuclear lanthanide(III) complexes of 8-hydroxyquinoline-7-carbaldehyde-(isonicotinyl)hydrazone

Abstract

Binuclear complexes [LnL(NO₃)(H₂O)₂]₂ were prepared from the Schiff base 8-hydroxyquinoline-7-carbaldehyde-(isonicotinyl)hydrazone (H₂L) and equivalent molar amounts of Ln(NO₃)₃· 6H₂O (Ln = La³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Dy³⁺, Ho³⁺, Er³⁺, Yb³⁺), respectively. The ligand is dibasic tetradentate and the dimerization occurs through the phenolate oxygen atoms leading to a central four-membered (LnO)₂-ring. The ligand and all the Ln(III) complexes can bind to calf thymus DNA through intercalation with binding constants of 10⁵–10⁶ (mol L⁻¹)⁻¹, and they show strong scavenging abilities on hydroxyl radicals and superoxide radicals. The values of SC ₅₀ of Ln(III) complexes for HO^• and are 2.344−13.33 and 4.459−28.48 µmol L⁻¹, respectively. Ln(III) complexes present stronger binding abilities to DNA and stronger anti-oxidation properties than ligand. Complex containing hydroxyl unit shows stronger scavenging abilities on hydroxyl radical, while complex containing N-heteroaromatic substituent shows stronger scavenging abilities on superoxide radicals. Furthermore, earlier rare metal complexes show stronger scavenging abilities on both hydroxyl radicals and superoxide radicals.

Keywords:

• 8-Hydroxyquinoline-7-carbaldehyde
• Schiff-base ligand
• Lanthanide(III) complexes
• Calf thymus DNA
• Intercalation
• Anti-oxidation properties

Acknowledgments

This study was supported by China NNSF (20975046) and Gansu Educational Fund SRP (1010B-04).