Synthesis, Characterization, DNA Interaction, and Antitumor Activities of La (III) Complex with Schiff Base Ligand Derived from Kaempferol and Diethylenetriamine

Abstract

A novel La (III) complex, [LaL(H2O)3]NO3·3H2O, with Schiff base ligandLderived from kaempferol and diethylenetriamine, has been synthesized and characterized by elemental analysis, IR, UV-visible,1H NMR, thermogravimetric analysis, and molar conductance measurements. The fluorescence spectra, circular dichroism spectra, and viscosity measurements and gel electrophoresis experiments indicated that the ligandLand La (III) complex could bind to CT-DNA presumably via intercalative mode and the La (III) complex showed a stronger ability to bind and cleave DNA than the ligandLalone. The binding constants (Kb) were evaluated from fluorescence data and the values ranged from 0.454 to 0.659 × 105L mol−1and 1.71 to 17.3 × 105L mol−1for the ligandLand La (III) complex, respectively, in the temperature range of 298–310 K. It was also found that the fluorescence quenching mechanism of EB-DNA by ligandLand La (III) complex was a static quenching process. In comparison to free ligandL, La (III) complex exhibited enhanced cytotoxic activities against tested tumor cell lines HL-60 and HepG-2, which may correlate with the enhanced DNA binding and cleaving abilities of the La (III) complex.