DNA Binding and Antitumor Activity of a New Fluores cent ProbeEu(Ⅲ)-Complex Containing 4-Methyl-Coumarin Moiety

A new europium(Ⅲ)complex containing(4-Methyl-2-oxo-2 H-chromen-7-yloxy)-acetic acid moiety(CMMC)was synthesized,characterized,and confirmed as antitumor agent and fluorescent probe.The spectroscopic measurements of Eu(Ⅲ)in the presence of CMMC were obtained in different solvents.The results show that the strongest Eu(Ⅲ)emission bands were monitored in iso-propyl alcohol while the weakest Eu(Ⅲ)emission band was observed in acetonitrile.The interaction of Eu(Ⅲ)-(CMMC)2 complex with DNA was monitored using absorption and emission techniques.From fluorescence titration measurements,the binding constants of DNA with Eu(Ⅲ)-(CMMC)_2 complex were found to be 1.04×10~5 L·mol^(-1) in Tris-HCl and 1.17×10~7 L·mol^(-1) in DMSO-Tris-HCl buffer(9∶1 V/V).Hypochromism was observed from the absorption titration experiment which indicates the intercalation of Eu(Ⅲ)-complex between the base pair of DNA.This result further confirmed by fluorescent Ethidium bromide displacement assay.The fluorescence calibration curve was used for the determination of DNA with LOD of 1.2 ng in DMSO-Tris-HCl buffer(9∶1 V/V)and 5 ng in Tris-HCl buffer.The preliminary antitumor investigation shows promising cytotoxicity against MDA-MB-231,MCF-7(mammary cancer),and PC-3(prostate carcinoma)cell lines with IC50 values of 40.63,25.42 and 30.25μmol·L^(-1),respectively.