Investigation of crystallographic structure, in vitro cytotoxicity and DNA interaction of two La(III) and Ce(IV) complexes containing dipicolinic acid and 4-dimethylaminopyridine

Abstract

The compound, [dmpH]2[pydc] (L) as ligand was synthesized by the proton-transfer reaction of pyridine-2,6-dicarboxylic acid (pydcH2) with 4-dimethylaminopyridine (dmap). The new coordination complexes of [dmpH]2[La2(pydc)4(H2O)4]·2H2O (1) and [dmpH]2[Ce(pydc)3]·2H2O (2) were prepared from the reaction of the ligand with La(NO3)3·6H2O and Ce(SO4)2·4H2O metal salts, respectively. All structures were characterized by X-ray crystallography. Cytotoxicity of compounds was tested under MTT method, against HT29 (a human colon adenocarcinoma), HepG2 (a human liver hepatocellular carcinoma) and HL60 (a human lymphocyte) cell lines. Complex (1) with IC50 values of about 1–100 μM was more active than other compounds on all three cell lines. The strongest anti-proliferative effect was observed for (1) toward HL60 cell line with IC50 value equal to 1 μM. High cytotoxicity of complexes indicated that they can be further evaluated for cancer treatment in the next set. UV–Vis absorption spectroscopy, emission titration and viscosity were employed to investigate the mode of interaction between (L), (1) and (2) with calf-thymus DNA. All studies represented that (L), (1) and (2) interact with CT-DNA via intercalation mode. A direct correlation was recognized between inhibitory and DNA interaction potent of the compounds. Also, the results of molecular docking were in agreement with obtained experimental data of DNA interaction.