槲皮素与锌离子结合性质及抗氧化活性研究

Studies on the binding properties of Zn^(2+) ion to quercetin and the antioxidant activities

目的研究槲皮素与其锌离子(Zn^(2+))配合物的抗氧化性能。方法通过紫外/可见分光光度法测定槲皮素与Zn^(2+)的结合比例及结合常数,结合核磁共振技术确定其结合位点,以1,1-二苯基苯肼(DPPH)为探针,比较研究槲皮素与其Zn^(2+)配合物的抗氧化性能。结果当槲皮素中低于2个酚羟基被中和时,槲皮素与Zn^(2+)的饱和结合比为2∶1;当超过3个酚羟基被中和时,槲皮素与Zn^(2+)的结合比为1∶1,此时槲皮素-Zn^(2+)的表观结合常数为2.42×106 M-1。槲皮素的3′-O、4′-O参与了与Zn^(2+)的配位。槲皮素-Zn^(2+)配合物清除DPPH自由基的活性比槲皮素本身高出2.3倍。结论 Zn^(2+)可与槲皮素形成稳定的配合物,且其比槲皮素本身具有更高效的抗氧化性能,这为传统中药槲皮素的应用提供了新思路。

Objective To study the anti-oxidation properties of Zn^（2＋）-quercetin complexes.Methods The binding stoichiometric ratios and the binding constant of Zn^（2＋）to quercetin were measured with UV-Vis spectroscopy.The binding sites on quercetin were determined via 1 H NMR spectroscopy.The antioxidant activities of Zn^（2＋）-quercetin complexes were compared to quercetin by scavenging DPPH radical method.The binding ratio of Zn^（2＋）to quercetin depends on neutralization of phenol groups of quercetin.Results The binding ratio of Zn^（2＋）to quercetin is 1∶2 when less than two OH groups were deprotonated.The binding ratio is 1∶1 when more than three OH groups were deprotonated.The apparent binding constant is 2.42×106 M-1 for the 1∶1 Zn^（2＋）-quercetin complex.The 3′-OH and 4′-OH of quercetin are involved in the Zn^（2＋）binding.The scavenging DPPH radical activity of Zn^（2＋）-quercetin complex is 2.3 times of quercetin.Conclusion These results provide a new insight to expand applications of this traditional Chinese medicine.