A displacement test based on the interaction between the flavonoid quercetin and an excess of metal chloride allows the determination of the binding constant for the reaction between quercetin and Ca2+,Mg^2+and Ni^2+....A displacement test based on the interaction between the flavonoid quercetin and an excess of metal chloride allows the determination of the binding constant for the reaction between quercetin and Ca2+,Mg^2+and Ni^2+.The values obtained were 2.20±1.77×10^3 for Ca^2+,1.37±0.59×10^3 for Mg^2+and 7.03±1.04×10^4 for Ni^2+,and all interactions showed type 1:1 stoichiometry,as determined by titration and by the method of continuous variations(Job’s method).The complexion effect was observed qualitatively through a colorimetric change in the medium(yellow→neon yellow)and spectroscopically through a bathochromic shift in the absorption band of quercetin in the presence of metals.This investigation serves as a tool for the development and testing of materials capable of capturing toxic metal ions or favoring the absorption of beneficial ions(in relation to the human metabolism)through the construction of efficient bioorganic systems.The results reported herein allow understanding of this detection system,indicating the following ascending order of the binding constants(Mg^2+<Ca^2+<Al^3+<Ni^2+).展开更多
基金The authors thank the Instituto Federal do Parana(IFPR),the IFPR by Programa de Apoio ao Desenvolvimento Tecnologico e Inovac,ao(PRADI),and Conselho Nacional de Desenvolvimento Cientifico e Tecnologico(CNPq-Brazil).
文摘A displacement test based on the interaction between the flavonoid quercetin and an excess of metal chloride allows the determination of the binding constant for the reaction between quercetin and Ca2+,Mg^2+and Ni^2+.The values obtained were 2.20±1.77×10^3 for Ca^2+,1.37±0.59×10^3 for Mg^2+and 7.03±1.04×10^4 for Ni^2+,and all interactions showed type 1:1 stoichiometry,as determined by titration and by the method of continuous variations(Job’s method).The complexion effect was observed qualitatively through a colorimetric change in the medium(yellow→neon yellow)and spectroscopically through a bathochromic shift in the absorption band of quercetin in the presence of metals.This investigation serves as a tool for the development and testing of materials capable of capturing toxic metal ions or favoring the absorption of beneficial ions(in relation to the human metabolism)through the construction of efficient bioorganic systems.The results reported herein allow understanding of this detection system,indicating the following ascending order of the binding constants(Mg^2+<Ca^2+<Al^3+<Ni^2+).
