School of Pharmacy, Lanzhou University, Lanzhou 730000, China.
College of Pharmacy, Gansu University of Chinese Medicine, Lanzhou 730000, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2023 Dec 5;302:123115. doi: 10.1016/j.saa.2023.123115. Epub 2023 Jul 8.
Acetylcholinesterase (AChE) is an important therapeutic target for the treatment of Alzheimer's disease (AD), and the development of natural AChE inhibitors as candidates has played a significant role in drug discovery. In this study, the inhibition mechanisms of four ellagitannins, punicalagin, chebulinic acid, geraniin and corilagin, from Terminalia chebula fruits on AChE were investigated systematically by a combination of inhibition kinetics, multi-spectroscopic methods and molecular docking. The kinetic results showed that punicalagin, chebulinic acid and geraniin exhibited strong reversible inhibitory effects on AChE in an uncompetitive manner with the IC values of 0.43, 0.50, and 0.51 mM, respectively, while corilagin inhibited AChE activity in a mixed type with the IC value of 0.72 mM. The results of fluorescence and UV-vis spectra and fluorescence resonance energy transfer (FRET) revealed that four ellagitannins could significantly quenched the intrinsic fluorescence of AChE though a static quenching along with non-radiative energy transfer. Thermodynamic analyses showed that values of ΔG, ΔH and ΔS were negative, indicating that all binding processes were spontaneous, and the hydrogen bonding and Van der Waals forces might make a great contribution to the formation of inhibitor-AChE complexes. The synchronous fluorescence, three-dimensional (3D) fluorescence, UV-vis, and FT-IR spectra studies suggested that four ellagitannins could lead to alterations in the micro-environment and secondary structure of AChE, and thus the conformational change of AChE. Moreover, molecular docking demonstrated that four ellagitannins could interacted with main amino acid residues of AChE with affinity energies ranging from -9.9 to -8.7 kJ/mol, and further confirmed the above experimental results. This study provided valuable findings for the potential application of four ellagitannins as promising candidates in the exploration of natural AChE inhibitors for the treatment of AD.
乙酰胆碱酯酶（AChE）是治疗阿尔茨海默病（AD）的重要治疗靶点，天然 AChE 抑制剂的开发作为候选药物在药物发现中发挥了重要作用。在这项研究中，通过结合抑制动力学、多光谱方法和分子对接，系统研究了来自诃子果实的四种鞣花单宁，鞣花酸、没食子酸、石榴宁和柯里拉京，对 AChE 的抑制机制。动力学结果表明，鞣花酸、鞣花酸和石榴宁以非竞争性方式对 AChE 表现出强烈的可逆抑制作用，IC 值分别为 0.43、0.50 和 0.51 mM，而柯里拉京以混合类型抑制 AChE 活性，IC 值为 0.72 mM。荧光和紫外可见光谱以及荧光共振能量转移（FRET）的结果表明，四种鞣花单宁可以通过静态猝灭和非辐射能量转移显著猝灭 AChE 的固有荧光。热力学分析表明，ΔG、ΔH 和 ΔS 的值为负值，表明所有结合过程都是自发的，氢键和范德华力可能对抑制剂-AChE 复合物的形成做出了很大贡献。同步荧光、三维（3D）荧光、紫外可见和傅里叶变换红外光谱研究表明，四种鞣花单宁可导致 AChE 的微环境和二级结构发生变化，从而导致 AChE 的构象发生变化。此外，分子对接表明，四种鞣花单宁可以与 AChE 的主要氨基酸残基相互作用，亲和力能范围为-9.9 至-8.7 kJ/mol，进一步证实了上述实验结果。本研究为将四种鞣花单宁作为有前途的候选药物，用于探索天然 AChE 抑制剂治疗 AD 提供了有价值的发现。
