Synthesis, characterization, antioxidative and antitumor activities ofsolid quercetin rare earth(III) complexes

摘要

Eight rare earth metal(III) complexes with quercetin ML3. 6H(2)O [L=quercetin (3-OH group deprotonated); M=La, Nd, Eu, Gd, Tb,Dy, Tm and Y] have been synthesized and characterized by elemental analysis, complexometric titration, thermal analysis, conductivity, IR, UV, (HNMR)-H-1 and fluorescence spectra techniques as well as cyclic voltammetry. The quercetin:metal stoichiometry and the equilibrium stability constant for metal binding to quercetin have been determined. The antioxidative and antitumor activities of quercetin . 2H(2)O and the complexes were tested by both the MTT and SRB methods. The results show that the suppression ratio of the complexes against the tested tumour cells are superior to quercetin . 2H(2)O. The property of LaL3. 6H(2)O reacting with calf thymus DNA was studied by fluorescence methods. The La-complex binding to DNA has been determined by fluorescence titration in 0.05 M Tris-HCl, 0.5 hi NaCl buffer (pH 7.0). The results indicate that the interaction of the complex with DNA is very evident.