Department of Pharmacy, Liaocheng University, Liaocheng, Shandong 252000, China.
Institute of Biopharmaceutical Research, Liaocheng University, Liaocheng, Shandong 252000, China.
Int J Biol Macromol. 2021 May 1;178:424-433. doi: 10.1016/j.ijbiomac.2021.02.213. Epub 2021 Mar 1.
Amyloid proteins were recognized as the crucial cause of many senile diseases. In this study, the inhibitory effects of Sennoside A (SA) and Sennoside C (SC) on amyloid fibrillation were evaluated by the combination of biophysical approaches and molecular docking tool using human lysozyme (HL) as amyloid-forming model. The results of thioflavin-T (ThT), 8-anilino-1-naphthalenesulfonic acid (ANS) and congo red (CR) assays indicated that both SA and SC could inhibit the amyloid fibrillation of HL in a dose-dependent manner. The IC value of SA and SC on HL fibrillation was 200.09 μM and 186.20 μM, respectively. These findings were further verified by transmission electron microscopy (TEM) and atomic force microscopy (AFM), which showed that the addition of SA or SC could sharply reduce the amyloid fibrillation of HL. Additionally, the interactions of HL with SA and SC were investigated by steady-state fluorescence spectra and molecular docking studies. The results suggested that both SA and SC could bind to the binding pocket of HL and form a stable complex mainly via hydrogen bonds, van-der-Waals forces and hydrophobic interactions. In conclusion, our experiments revealed that both SA and SC can significantly inhibit amyloid fibrillation of HL.
淀粉样蛋白被认为是许多衰老疾病的关键原因。在这项研究中，我们通过生物物理方法和分子对接工具的结合，以人溶菌酶（HL）为淀粉样形成模型，评估了番泻苷 A（SA）和番泻苷 C（SC）对淀粉样纤维形成的抑制作用。硫黄素 T（ThT）、8-苯胺-1-萘磺酸（ANS）和刚果红（CR）测定结果表明，SA 和 SC 均可剂量依赖性地抑制 HL 的淀粉样纤维形成。SA 和 SC 对 HL 纤维形成的 IC 值分别为 200.09 μM 和 186.20 μM。透射电子显微镜（TEM）和原子力显微镜（AFM）的进一步验证表明，添加 SA 或 SC 可明显减少 HL 的淀粉样纤维形成。此外，我们通过稳态荧光光谱和分子对接研究考察了 HL 与 SA 和 SC 的相互作用。结果表明，SA 和 SC 均可与 HL 的结合口袋结合，并通过氢键、范德华力和疏水相互作用形成稳定的复合物。总之，我们的实验结果表明，SA 和 SC 均可显著抑制 HL 的淀粉样纤维形成。
