靶向细胞色素bc1复合物Qi位点的新型杀菌剂的设计与合成

As an essential part of cellular respiration chain, cytochrome bc1 complex is an important target for the discovery of agricultural fungicides. The crystallographic study showed bc1 complex has two active sites: Qo site and Qi site. In recent years, the pathogen resistance of commercialized cytochrome bc1 complex inhibitors developed very quickly, after their wide application in crop protection. Therefore, design and synthesis of novel efficient cytochrome bc1 complex Qo site and Qi site inhibitors with high activity and low resistance risk attract more and more attentions from scientists. In our previous research, the pharmacophore-linked fragment virtual screening (PFVS), a novel method of fragment based rational design has been developed, and the first picomolar-range Qo site inhibitors of the cytochrome bc1 complex were discovered by employing PFVS. To expand the study on the discovery of novel efficient cytochrome bc1 complex inhibitors with high activity and low resistance risk, we will focus on the design and synthesis of Qi site inhibitors in this project starting from the investigation of the binding modes of existing Qi site inhibitors.Firstly, the PFVS method will be applied to find new inhibitors based on the estabilishment of pharmacophore model of Qi site inhibitors. Secondly, since a incorporated cavity is formed by Qo site of one monomer and Qi site of the other monomer within the dimer, the in situ click chemistry strategy is to be applied to synthesize bc1 complex dual-site inhibitors by using the incorporated cavity as template. In general, with the help of research cycles of "design - synthesis - inhibitor screening", novel bc1 complex Qi site inhibitors with high activity and low risk of resistance hopefully could be identified by the above two strategies, which can not only provide new lead compounds for agrochemical fungicide discovery, bust also offer novel probes for studying the electron transfer mechanisms.

作为细胞呼吸链的必要组成部分，细胞色素bc1复合物是农用杀菌剂开发的重要靶标。bc1复合物有两个活性位点：Qo位点和Qi位点。近年来，商品化bc1复合物抑制剂的抗性发展极为迅速,针对这两个位点设计合成具有低抗性风险的抑制剂引起了研究者的广泛兴趣。前期工作中，我们发展了药效团连接碎片虚拟筛选的分子设计新方法，获得了皮摩尔水平抑制活性的Qo位点抑制剂。为拓展低抗性风险的bc1复合物抑制剂的研究，本项目在系统研究现有Qi位点抑制剂作用机制的基础上，拟开展新型Qi位点抑制剂的设计与合成。一方面，提炼现有Qi位点抑制剂的药效团，利用药效团连接的碎片筛选方法开展新抑制剂的设计；另一方面，结合bc1复合物二聚体复合空腔的特点，采用原位点击化学策略合成bc1复合物的双位点抑制剂。通过以上两种策略，力争通过"边设计-边合成-边测试"的协同研究循环，获得具有高活性和低抗性风险的靶向Qi位点的杀菌剂候选化合物。

作为细胞呼吸链的必要组成部分，细胞色素bc1 复合物是农用杀菌剂开发的重要靶标。bc1 复合物有两个活性位点：Qo 位点和Qi 位点。本项目执行期间，我们深入研究了代表性Qi 位点抑制剂的作用机理，阐明了抗霉素A对bc1复合物慢紧结合的作用机制。随后，我们分别采用三种策略Qi位点抑制剂进行设计和改造。（a）以吲唑磺菌胺为模板，引入具有广泛生物活性的三氮唑和二苯醚单元。（b）运用PFVS方法设计具有新型骨架的化合物。（c）采用原位点击化学方法，合成具有高亲和力的双位点bc1复合物抑制剂。最终，我们发现了对Qi 位点具有纳摩尔活性的二氢喹啉酮类先导化合物。本项目的研究成果发表在农药化学和化学生物主流学术期刊上，共12篇。部分成果已经申请了两项中国发明专利和两项国际PCT专利，并转让给企业进行后续的产业化开发。