以乙酰胆碱酯酶为靶标的虚拟筛选研究

发布时间：2018-12-23 20:54

【摘要】：阿尔茨海默病(Alzheimer's disease, AD)是严重威胁当代老年人健康的疾病,导致中枢神经系统进行性退变进而影响患者的认知功能、记忆功能、语言功能、视空间功能,所以也被称为老年痴呆症。然而,老年痴呆症的发病机制还不是十分清楚,有待更加深入详细的研究。胆碱不足是导致阿尔茨海默病产生的一个主要原因,因此具有增强胆碱作用的药物在老年痴呆症的治疗方面发挥了重要作用。目前治疗AD的主要药物有他克林(Tacrine)、利伐斯的(Rivastigmine)、石杉碱甲(Hu-perzineA)、多奈哌齐(Donepezil)等,它们都是通过与乙酰胆碱酯酶(AChE)结合,对酶活性产生抑制作用,达到一定的治疗效果。然而现有的商品化的AChE抑制剂的临床效果有限,并且在治疗过程中都伴随着不同程度的毒副作用,寻找新型高活性的AChE抑制剂小分子是很有必要的。他克林褪黑激素杂合体系列抑制剂小分子对人体乙酰胆碱酯酶(h-AChE)均呈现出很高的抑制活性,明显高于之前已报道的系列药物分子,达到了pM级别。本文从该系列高活性化合物出发,通过分子对接后,进行受体和配体结合自由能的计算,发现结合自由能的计算值和生物测试活性值有很好的线性相关性,确定了分子对接结合模式的正确性。通过对结合自由能的能量分解,可以找到配体与人体乙酰胆碱酯酶(h-AChE)相互作用中起关键作用的重要氨基酸残基。通过基于受体的药效团模型(Structure Based Pharmacophore,SBP)生成药效团模型,参照之前确定的活性腔中重要的氨基酸残基,对生成的药效团中重要的元素特征进行保留,然后将前期的系列高活性分子和未知活性的分子组成分子库对药效团的合理性进行验证,高活性分子可以被很好的筛选出来,验证了我们构建的药效团模型的有效性。最后将该药效团对自己构建的分子库进行虚拟筛选,筛选到含有他克林环、含有酰胺键的亚甲基长链以及香豆素环片段的化合物分子,通过分子对接了解该类化合物分子与受体蛋白的合理结合模式,然后对该类分子进行生物活性测试,发现他们均具有活较好的活性,其中最优的分子其体外酶活相对经典抑制剂他克林提高了一倍多,为今后抑制剂分子的优化提供了重要的指导意义。
[Abstract]:Alzheimer's disease (Alzheimer's disease, AD) is a serious threat to the health of the elderly, leading to progressive degeneration of the central nervous system, which affects the cognitive function, memory function, language function, visual and spatial function of the patient. So it's also called Alzheimer's disease. However, the pathogenesis of Alzheimer's disease is not very clear, need more in-depth and detailed research. Choline deficiency is a major cause of Alzheimer's disease, so drugs that enhance choline play an important role in the treatment of Alzheimer's disease. At present, the main drugs used in the treatment of AD are (Rivastigmine), Huperzine A (Hu-perzineA) of tacrine (Tacrine), Livas, Donepezil (Donepezil) and so on. They all inhibit the enzyme activity by binding with acetylcholinesterase (AChE). To achieve a certain therapeutic effect. However, the clinical effects of commercial AChE inhibitors are limited, and in the course of treatment, with varying degrees of toxic side effects, it is necessary to find new and highly active small molecules of AChE inhibitors. The small molecules of tacrine melatonin heterozyme showed high inhibitory activity on human acetylcholinesterase (h-AChE), which was significantly higher than that of the previously reported series of drug molecules, and reached the pM level. Starting from this series of highly active compounds, the binding free energy of receptor and ligand was calculated by molecular docking. It was found that there was a good linear correlation between the calculated value of binding free energy and the bioassay activity value. The correctness of the molecular docking mode was determined. Through the energy decomposition of binding free energy, the important amino acid residues that play a key role in the interaction between ligand and human acetylcholinesterase (h-AChE) can be found. The pharmacophore model was generated by receptor-based pharmacophore model (Structure Based Pharmacophore,SBP), and the important elemental characteristics of the generated pharmacophore were preserved by referring to the important amino acid residues in the previously determined active cavity. Then, the rationality of the pharmacophore was verified by a series of molecular libraries of high active molecules and unknown active molecules, and the high active molecules could be well screened out, which verified the validity of the pharmacophore model we constructed. Finally, the pharmacophore was used for virtual screening of the constructed molecular library, and the compounds containing tacrine ring, methylene chain containing amide bond and coumarin ring fragment were screened out. Through molecular docking to understand the reasonable binding mode between the molecules and receptor proteins, and then to test the bioactivity of these molecules, we found that they all have good activity. The in vitro enzyme activity of the optimal molecule is more than double that of the classical inhibitor tacrine, which provides important guidance for the optimization of the inhibitor molecule in the future.
【学位授予单位】：华中师范大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：R749.16

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