Synthesis, characterization, DNA binding properties and antioxidant activity of Ln(III) complexes with hesperetin-4-one-(benzoyl) hydrazone.

Novel Ln(III) complexes with hesperetin-4-one-(benzoyl) hydrazone (H(4)L) have been synthesized and characterized. Electronic absorption spectroscopy, fluorescence spectra, ethidium bromide displacement experiments, iodide quenching experiments, salt effect and viscosity measurements indicate that the ligand and Ln(III) complexes, especially the Nd(III) complex, strongly bind to calf thymus DNA, presumably via an intercalation mechanism. The intrinsic binding constants of the Nd(III) complex and ligand with DNA were 2.39 x 10(6) and 2.70 x 10(5)M(-1), respectively. Furthermore, the antioxidant activity of the ligand and Ln(III) complexes was determined by superoxide and hydroxyl radical scavenging method in vitro, which indicate that the ligand and Ln(III) complexes have the activity to suppress O(2)(-) and HO() and the Ln(III) complexes exhibit more effective antioxidant activity than the ligand alone.