以肺炎链球菌WalK酶HATPase_c结构域为靶点的新型咪唑类抗菌药物的合成及其抗菌效应研究

Two-component system (TCS) is a unique signal transduction pathways which conservatively present in Gram-positive bacteria, that not yet found in mammalian cells, therefore the bacterial TCS has become an important target for antimicrobial drug research. We have got six compounds with significantly antibacterial activity for the histidine kinase WalK HATPase-c target of TCS from S.pn through virtual screening and experiment that is closely related to S.pn survive. However, we have found an imidazole derivative which has the highest antibacterial activity in vitro, but not satisfied in vivo. Therefore, the study is to use the imidazole derivative as lead compound to design and synthesize a series of novel Imidazoles derivatives by calculate the ability of which combine with the three-dimensional structure of HATPase-c domain. To identify its antibacterial activity and drug toxicity through the minimal inhibitory concentration and minimal bactericidal concentration experiment and cytotoxic test,then to identify whether it has a broad spectrum of activity against gram-positive bacteria by animal models of mice in vivo.In order to assess its safety and effective use through the pharmacokinetic analysis.We expect to obtain low toxicity and good antibacterial effect pharmaceutical compounds for the foundation to develop a new class drugs with independent intellectual property rights by the research.

双组分系统（TCS）是保守存在于革兰阳性菌的一种特有的信号转导途径，由于哺乳动物细胞内尚未发现类似调控系统，因此细菌TCS已成为抗菌药物研究的重要靶点。本课题组以肺炎链球菌TCS中与细菌生存密切相关的组氨酸激酶WalK酶HATPase-c结构域为靶点，通过虚拟筛选和实验验证获得6个具有明显抑菌活性的化合物。然而，我们发现其中的一种咪唑类衍生物在体外具有最高的抗菌活性，但体内的抗细菌感染效果并不理想。因此，本课题拟以该化合物为先导结构，设计并合成一系列新型咪唑类衍生物；通过最低抑菌或杀菌浓度实验、细胞毒试验等鉴定其抗菌活性及药物毒性，同时鉴定其是否具有广谱的抗革兰阳性菌的活性；通过小鼠动物模型观察其体内抗菌效果，并通过药动学分析获得其基本的药动学参数，便于其安全有效的使用。通过本研究可获得毒性低、体内抗菌效果好的化合物，为开发具有自主知识产权的1类新药奠定坚实的基础。

本课题组前期采用分子对接的方法，筛选出以肺炎链球菌WalK酶HATPase-c结构域为作用靶点的咪唑类化合物6，其在体外展示出较好的抗菌活性，但其体内保护效果不理想，且细胞毒性较高。本研究拟以肺炎链球菌WalK酶HATPase-c结构域（CA结构域）三维结构中氨基酸功能残基为药物作用靶点，采用化合物6为先导结构模板，设计并合成系列新型咪唑类抗菌化合物。通过对其中可溶性较好的3种化合物和三种不同序列长度的WalK蛋白相互作用，验证新型化合物抗菌靶点位于肺炎链球菌WalK酶CA结构域；通过体外实验考查化合物抗菌活性及毒性反应；通过建立小鼠肺炎链球菌感染模型，检测其体内抗菌效应。本研究首次证实新合成的4号咪唑类化合物可能是未来治疗肺炎链球菌感染的新型药物，后续实验将着重其药物代谢学、药物动力学方面的深入研究，以期筛选出抗革兰氏阳性细菌感染的广谱新型咪唑类化合物。