Synthesis, characterization, cytotoxic activities, and DNA-binding properties of the La(III) complex with Naringenin Schiff-base

A new Naringenin Schiff-base ligand (H3L) and its complex, [La(H2L)(2)(NO3)center dot 3H(2)O], have been synthesized and characterized on the basis of elemental analyses, molar conductivities, mass spectra, H-1 NMR, thermiogravimetry/differential thermal analysis (TG-DTA), UV spectra, and IR spectra. Spectrometric titrations, ethidium bromide displacement experiments, and viscosity measurements indicate that the two compounds, especially the La(III) complex, strongly bind with calf-thymus DNA, presumably via an intercalation mechanism. The intrinsic binding constants of the La(III) complex and ligand with DNA were 1.83 x 10(7) and 9.46 x 10(5) M-1, respectively. Comparative cytotoxic activities of the La(III) complex and ligand were also determined by MTT [3-(4,5-ditnethyl-2-thiazoyl)-2,5-diphenyl-2H-teti-azolium bromide] and SRB (sulforhodamine B) methods. The results showed that the La(III) complex had significant cytotoxic activity against the tested cells. (c) 2005 Elsevier Ltd. All rights reserved.