基于靶标结构设计丁酰胆碱酯酶抑制剂并评价其抗中、重度阿尔茨海默症的活性

Alzheimer’s disease (AD) severely threatens the health of human beings. Till now, acetylcholinesterase inhibitors still play a central role for the treatment of AD. However, they can easily cause peripheral cholinergic side-effects, while the therapeutic effect is very limited for advanced AD. So far, it is discovered that BuChE acts as a significant factor in the cholinergic system of advanced AD patients, and inhibition of BuChE can avoid the side-effects caused by AChE inhibitors, therefore, it is now considered as a promising target for the treatment of advanced AD and deserves expanded researches. This proposal is derived from the previous National Natural Science Foundation of China (youth project), in which the applicant identified a new BuChE selective inhibitor 8012-9656 with activity in nanomolar range. Based on the results, in this project the applicant will perform researches listed as follows: 1) structure-guided molecular design and synthesis of 8012-9656 derivatives, as well as the effort in identifying new scaffolds as potent and selective BuChE inhibitors; 2) in vitro and in vivo evaluation of the BuChE inhibitor and the related mechanism. Based on these researches, the applicant will explore the molecular design strategy of selective BuChE inhibitors, as well as its advantage for AD treatment. Finally, this project is aimed to identify 1~2 efficient, safe and selective BuChE inhibitors for further pre-clinical study, which will become the foundation for the development of new drugs treating advanced AD.

阿尔茨海默症（AD）严重危害人类健康，目前临床上仍以乙酰胆碱酯酶（AChE）抑制剂为主要治疗药物，但易产生外周胆碱能副作用且对中、重度AD患者无能为力。已发现丁酰胆碱酯酶（BuChE）在中、重度AD患者的胆碱能系统中具有关键作用，且抑制BuChE不易引起AChE抑制剂所致的副作用，可能具有更高的安全性，有望成为治疗中、重度AD的新策略。本项目基于先前国家自然青年基金项目的研究结果，以IC50为nM级的化合物8012-9656为先导物，深入开展如下研究：1）基于靶标结构设计、合成高活性、高选择性BuChE抑制剂，努力拓展全新的分子骨架；2）评价目标分子的体内外活性，并在细胞和分子水上研究活性化合物的作用机制。通过上述研究，探究选择性BuChE抑制剂的设计策略及AD治疗优势，并期望发现1-2个高效、安全且具选择性作用的BuChE抑制剂进入临床前研究，为获得治疗中、重度AD的药物奠定坚实基础。

当前，中国/全球老龄化加剧，阿尔茨海默症（Alzheimer’s disease，AD）患者日益增多，发展新型AD治疗药物服务于国家大健康战略的重大需求。丁酰胆碱酯酶（Butyrylcholinesterase，BChE）具有水解乙酰胆碱（Acetylcholine，Ach）的代偿能力，且与Aβ沉积密切相关，被认为是治疗阿尔茨海默病的潜在靶点。在本项目中，我们应用了分级虚拟筛选方案，然后进行活性筛选与评估。合成了苗头化合物8012-9656（eqBChE IC50 = 0.18 ± 0.03 μM，hBChE IC50 = 0.32 ± 0.07 μM）。它以非竞争性方式抑制BChE，并能占据结合袋与靶标形成多种相互作用。然后，我们以8012-9656为先导进行了药物化学优化，并对其构效关系（structure–activity relationship，SAR）进行了探索。优选分子S06-1011（hBChE IC50 = 16 nM）和S06-1031（hBChE IC50 = 25 nM）展现了优异的BChE抑制能力，且安全性良好。优选化合物在东莨菪碱和Aβ1–42肽诱导的认知缺陷模型中表现出神经保护作用和改善认知的能力。接着，我们进行了进一步的活性和成药性优化，获得两个优选化合物（7，eqBChE IC50 = 2.94 nM，hBChE IC50 = 34.6 nM，and 20，eqBChE IC50 = 0.15 nM，hBChE IC50 = 45.2 nM）。化合物20的高稳定性有助于显著提高血药浓度和组织暴露，从而减少药效学实验中的给药量和有效剂量。两种优选分子均表现出显著的神经保护特性和认知改善活性，其作用机制为改善胆碱能系统，降低Aβ总量，增加胃饥饿素（ghrelin）含量。中心和外围同时调控极大地提高了BChE抑制剂的药效。考虑到对ghrelin水平的调控，抑制BChE不仅可以改善AD患者的症状，还可以改善患者的营养状况。本项目获得的结构全新的BChE抑制剂也为后续继续开发药物奠定了坚实的基础。