Synthesis, crystal structure, cytotoxicity and DNA interaction of 5,7-dichloro-8-quinolinolato-lanthanides

Four isostructural lanthanide complexes with 5,7-dichloro-8-quinolinoline (H-ClQ): [Sm(ClQ)3(H2O)2]·1.33EtOH·0.33H2O (1), [Eu(ClQ)3(H2O)2]·0.5EtOH, (2), [Tb(ClQ)3(H2O)2]·0.5EtOH (3) and [Ho(ClQ)3(H2O)2]·H2O (4) were synthesized, in which the lanthanide was coordinated by three ClQ−ClQ− anions and two aqua ligands. The in vitro cytotoxicities of complexes 1−4 against five human tumor cells were evaluated. The IC50 values of complexes 1−4 against BEL7404, HeLa and A549 were in the range 1.2–6.3, 3.5–6.6 and 10.8–25.2 μM, respectively; except for complex 3 toward BEL7404, they all exhibited enhanced cytotoxicity in comparison to H-ClQ. The binding properties of complexes 1−4 to DNA examined by various methods indicated that complexes 1−4 interacted with DNA more strongly than free quinolinoline, and intercalation was the most probable binding mode for both the complexes and quinolinoline.

Four lanthanide complexes with 5,7-dichloro-8-quinolinoline were synthesized. They exhibited enhanced cytotoxicity vs. 5,7-dichloro-8-quinolinol and lanthanide salts. Intercalation is the most probable binding mode for both the complexes and quinolinoline.Figure optionsDownload as PowerPoint slideHighlights
► Four lanthanide complexes with 5,7-dichloro-8-quinolinoline have been synthesized.
► The lanthanide complexes exhibited enhanced cytotoxicity.
► Intercalation is the most probable binding mode.