基于Kas的靶向天然产物Thiolactomycin的杀菌先导优化及其生物活性研究

Beta-ketoacyl-ACP synthase(Kas) is particularly an attractive target enzyme in the fatty acid synthesis, but there were no reports on the literature about the development of fungicide targeted Kas. Our previous studies discovered that the natural product thiolactomycin(TLM) had good inhibition activity against Fusarium graminearum and its fatty acid synthase. This proposal will conduct novel studies on the KAS target protein based novel fungicide development. Novel TLM skeleton derivatives will designed and synthesized to increase the affinity of TLM and KAS, improve the photostability of target compounds by the computer-aided rational drug design and "natural product common pharmacophore-directed" strategy. Biological evaluations at KAS target enzyme and antifungal activity in vitro and in vivo by pot test at green house against Fusarium graminearum will be used as indicators for studies on their 3D-QSAR and the action of mechanism of the corresponding highly active compounds to discover the highly active Kas targeted TLM derivatives. For the highly active compounds without KAS activity, their novel mechanism of action will be disclosed by multidisciplinary crosslinking of proteomics, transcriptomics, metabonomics and bioinformatics. The results of this study will provide highly active fungicidal lead compound and the theories foundation for the novel pesticide development.

Beta-ketoacyl-ACP synthase(Kas)是脂肪酸合成途径中的关键酶，申请人前期研究发现天然产物Thiolactomycin(TLM)对小麦赤霉病菌(Fusarium graminearum)及其脂肪酸合成酶具有很好的抑制作用。本项目拟开展基于真菌Kas为靶标、TLM为先导的杀菌剂原始创新研究，运用计算机辅助合理分子设计及“天然产物共同药效团导向”策略设计合成结构新颖的TLM衍生物，提高TLM与KAS的亲和力和光稳定性；以小麦赤霉病菌的Kas酶活性和离体及室内盆栽抑菌活性为评价指标，开展目标化合物的活性筛选及抑菌作用机制和三维定量构效关系（3D-QSAR）的研究，发现Kas靶向的高活性TLM衍生物；利用转录组学、蛋白质组学、代谢组学及生物信息学多组学交叉及分子生物学的手段，对Kas脱靶的高活性化合物开展作用靶标的寻找研究，为新农药的创制提供高效杀菌先导化合物和理论基础。

以活性天然产物为先导对结构进行衍生及优化，已成为新农药创制研究的前沿与热点领域，也是获得具有良好的环境相容性农药的有效途径之一。具有Thiolactomycin结构的五元杂环化合物广泛存在于天然产物中，具有多种生物活性，作用机理独特，与环境相容性较好等特点，引起了科研工作者广泛的研究兴趣。本项目利用生物等排电子原理和“天然产物共同药效团导向”策略，设计合成一系列具有五元杂环骨架的Thiolactomycin衍生物，并测试这些目标化合物对苹果腐烂病菌、玉米叶斑病菌、小麦赤霉病菌、番茄枯萎病菌等植物病原菌的生物活性，探讨结构多样性对生物活性的影响。研究结果表明大多数目标化合物均表现出一定的杀菌活性，部分化合物均有较高的抑制作用，具有较好的广谱性，其活性与对照药嘧菌酯、氟吡菌酰胺和多菌灵相当，建立了具有较高预测能力3D-QSAR模型，探讨了目标化合物的构效关系和作用机制。同时发现了目标化合物具有高除草活性。研究结果为发现高活性的杀菌活性化合物和除草活性化合物提供了理论支持。