School of Medicine, Shenzhen University, Shenzhen, Guangdong Province 518060 PR China.
State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian Province 361005, PR China.
Food Chem. 2019 May 30;281:28-35. doi: 10.1016/j.foodchem.2018.12.077. Epub 2018 Dec 23.
Anthraquinones, a class of naturally occurring polyphenolic compounds, exhibit a wide range of bioactivities. However, most free anthraquinones are lipophilic bioactive compounds. Bovine β-lactoglobulin (βLG), a major whey protein, has a high affinity for small hydrophobic compounds. In this study, the interactions between anthraquinones (rhein, emodin, and chrysophanol) and βLG were investigated by using fluorescence, circular dichroism (CD), Fourier-transform infrared spectroscopy (FTIR), and docking studies. These anthraquinones bound to the site near Trp19-Arg124 on βLG with a binding constant (Ka) between 10 and 10 L mol to form complexes, which changed the secondary structure of βLG, inducing an α-helix to β-sheet structure transition. The order of binding increased with an increasing polarity in the order of rhein > emodin > chrysophanol. In addition, the degree of radical scavenging capacity masking increased with an increasing binding affinity. Complexation with βLG significantly increases the hydrosolubility of anthraquinones.
蒽醌类化合物是一类天然存在的多酚类化合物，具有广泛的生物活性。然而，大多数游离蒽醌类化合物是亲脂性生物活性化合物。牛β-乳球蛋白（βLG）是一种主要的乳清蛋白，对小分子疏水性化合物具有高亲和力。在这项研究中，通过荧光、圆二色性（CD）、傅里叶变换红外光谱（FTIR）和对接研究，研究了蒽醌（rhein、大黄素和大黄酚）与βLG 之间的相互作用。这些蒽醌类化合物与βLG 上靠近 Trp19-Arg124 的位点结合，结合常数（Ka）在 10 到 104 L/mol 之间，形成复合物，从而改变了βLG 的二级结构，诱导α-螺旋向β-折叠结构转变。结合顺序随着极性的增加而增加，rhein>大黄素>大黄酚。此外，随着结合亲和力的增加，自由基清除能力掩蔽程度增加。与βLG 结合可显著提高蒽醌的水溶解度。
