新型鸭嘴花碱类二聚体多靶点抗AD配体的设计、合成及生物活性

Alzheimer's disease (AD) is a serious threat to the elderly health and life, which cannot be cured. Searching for multiple targets anti AD lead compounds is an important basis of developing medicines for AD. Vasicine alkaloid, with high safety, has antioxidant activity and inhibitory activities on AChE and Aβ fibril aggregation, which may has the potential of be the anti AD lead compounds. This project, vasicine alkaloid as precursor, is meant to synthesize 45 multiple targets anti AD vasicine dimers with “metal ion chelating- antioxidant- AChE inhibitor- Aβ fibril aggregation inhibitor” under the method of computer aided design. Test the abilities of dimers for metal chelating, antioxidant, AChE inhibitory, Aβ fibril aggregation inhibitory, through UV spectrophotometry, ABTS method, Ellman colorimetric method and Th-T immunofluorescence method. Build the 3D-QSAR models of dimers structures and activities, and optimize the structures using the method of comparative molecular force field. Test the impacts on PC12, injured by dimers to H2O2 and Aβ42, cell viability and apoptosis rate of dimmer, and evaluate the compounds’ protective capability and cytotoxicity for neurons. Evaluate the influence of dimers to Aβ42 in AD mice, using the activities of Morris water maze, and AChE, ChAT and SOD in hippocampus. This project is aimed at building the method for obtaining vasicine dimers with high efficiency and low toxicity, optimizing the structures and for the sake of providing targeting for drug candidates in AD therapy.

AD严重威胁老年人健康和生命。寻找多靶点抗AD先导是研发抗AD药物的基础。鸭嘴花碱有抗氧化和抑制AChE的活性，安全性高，有成为抗AD先导的潜能。本项目拟以3个鸭嘴花碱类化合物为前体，根据金属离子螯合剂和双位点AChEIs的特点，利用计算机辅助法，设计合成兼具“金属离子螯合-抗氧化-抑制AChE-抑制Aβ聚集”多靶点协同作用抗AD的鸭嘴花碱类二聚体45个。测试二聚体的金属离子螯合、抗氧化、抑制AChE和Aβ42聚集活性，利用比较分子力场法构建受试二聚体的3D-QSAR模型，优化结构。检测二聚体对H2O2和Aβ42致损的PC12细胞存活率和凋亡率的影响，评价其对神经细胞的保护能力及毒性。通过Morris水迷宫和小鼠海马组织中AChE、ChAT和SOD的活性，评价二聚体对Aβ42致AD小鼠的影响，旨在获得高效低毒鸭嘴花碱类二聚体的构建方法，并为AD的治疗提供1-2个靶向明确的多靶点候选药物。

多靶点药物被认为是治疗阿尔兹海默病（AD）最有前景的方法之一。鸭嘴花碱具有抗氧化和抑制AChE的活性，安全性高，有成为抗AD先导的潜能。本研究以前期得到的3个鸭嘴花碱类化合物为前体，设计合成了56个多靶点抗AD的鸭嘴花碱类二聚体。活性测试发现8个化合物对AChE的半数抑制浓度小于10nm；4个化合物（浓度20μM），对Aβ1-42的半数抑制率超过50%。完成了3个高活性化合物对H2O2和Aβ42致损PC12细胞的保护作用测试，评价了2个衍生物对AD小鼠关键生化指标的影响。化合物A-6对AChE的半数抑制浓度为8.22nM，对Aβ1-42的半数抑制浓度为12.65μM，抗氧化活性是trolox的1.97倍；同时，A-6可以降低小鼠脑内皮层和海马组织中AChE活性、缩短Aβ1-42致痴呆模型小鼠寻找平台的时间，改善痴呆小鼠的记忆力，具有成为多靶点抗AD潜能的先导化合物的潜能。本研究为鸭嘴花碱类天然产物开发成多靶点抗AD先导化合物提供了重要的理论基础和数据支持。