Institute of Chemical Industry of Forest Products, CAF, Jiangsu Province Biomass Energy and Materials Laboratory, Nanjing 210042, China.
Institute of Chemical Industry of Forest Products, CAF, Jiangsu Province Biomass Energy and Materials Laboratory, Nanjing 210042, China.
Food Chem. 2018 Oct 15;263:208-215. doi: 10.1016/j.foodchem.2018.05.009. Epub 2018 May 3.
The complex formation between a copper ion and the dietary flavonoid quercetin (QU) and its two glycosides hyperin (HY) and rutin (RU) was studied by the combined use of spectroscopic measurement and the chemometric method. The spectral changes of pH titration revealed two successively formed deprotonated species of QU: the first formed species was proposed to be the 3-hydroxyl group deprotonated QU, and the second was the quinone form QU, which was formed by oxidation after the hydroxyl groups in the B-ring were deprotonated at high pH values. Similar results were obtained for HY and RU with two deprotonated species forming at high pH values. UV/visible spectroscopy showed successive formation of CuL and CuL species of QU at pH 6.0, while only CuL was formed for HY and RU at this pH. Glycoside moieties in the C-ring of flavonoids decrease the conditional associated constants between flavonoids and Cu.
采用光谱测量和化学计量学方法研究了铜离子与膳食类黄酮槲皮素（QU）及其两种糖苷金丝桃苷（HY）和芦丁（RU）之间的配合物形成。pH 值滴定的光谱变化显示 QU 依次形成了两种去质子化物种：第一种形成的物种被提议为 3-羟基去质子化的 QU，第二种是醌式 QU，它是在 B 环上的羟基在高 pH 值下去质子化后氧化形成的。HY 和 RU 也得到了类似的结果，在高 pH 值下形成了两种去质子化的物种。紫外/可见光谱显示 QU 在 pH 6.0 时依次形成 CuL 和 CuL 物种，而 HY 和 RU 在该 pH 值下仅形成 CuL。黄酮类化合物 C 环上的糖苷部分降低了黄酮类化合物与 Cu 之间的条件关联常数。
