新型CYP51抑制剂：硝基苯并噁嗪类化合物的设计合成与构效关系研究

In research and discovery of new pesticides, studies of the selective interaction between biological active molecule and target enzyme is a key to obtain highly active lead compound. On the basis of CYP51 (sterol 14α-demethylase) of the crop fungus, we design novel nitro-1,3-benzoxazines and nitro-3,1-benzoxazines as CYP51 inhibitors by using biorational molecule design method. The synthesis of these compounds will also be investigated. Active compounds will be afforded by evaluation of the inhibitor activity of the mentioned compounds against the CYP51 and their fungicidal activity. Extensive studies on the interaction mechanism between the obtained biological active compound and CYP51, structure-activity relationship and structure optimization of the active compound will be carried out by rational combination of homology modeling, molecular docking, 3D-QSAR and experiment technology, to reveal the interaction law between the active compound and CYP51. 4-6 Novel inhibitors or lead compounds of nitrobenzoxazines with high activity against CYP51 will be possibly obtained through many cycles of design, synthesis, activity assay, structure-activity relationship research and structure optimization. The results of the project will provide important experimental and theoretical basis for molecule design of new pesticides based on the ligand and receptor.

在新农药创制研究中，生物活性小分子与靶酶之间的选择性相互作用研究是获得高活性先导结构的关键。本项目以农作物真菌CYP51（甾醇14α-去甲基化酶）为靶酶，采用生物合理分子设计法拟设计合成结构新颖的CYP51抑制剂：硝基取代1,3-苯并噁嗪和硝基取代3,1-苯并噁嗪类化合物。通过酶抑制活性及其杀菌活性测定的方法来筛选活性化合物。利用同源模建法、分子对接法、三维定量构效关系分析和实验技术的有机结合来开展活性化合物与靶酶的相互作用机理、构效关系和结构优化的研究，归纳活性化合物与靶酶相互作用规律。经过设计－合成－活性评价－构效关系研究－结构优化的多次循环，力争找到4-6个高活性的新型CYP51抑制剂或具有进一步研究价值的先导化合物。为基于配体－受体相互作用的新农药分子设计提供重要的实验基础和理论依据。

创制和开发结构新颖、高效、低毒的农药对国民经济稳定发展具有十分重要的意义，其中分子设计和获得高活性先导化合物是农药创制的关键。本项目采用生物合理设计法共设计合成了360余个目标化合物（苯并噁嗪类化合物）和相关化合物，研究了它们的合成方法，并对它们的结构进行了表征。测定了所合成化合物的杀菌活性和对有关CYP51酶的抑制活性。采用同源模建法构建了稻瘟病菌CYP51的三维结构，利用分子对接法对活性化合物与稻瘟病菌CYP51的相互作用机理和规律进行了研究，探索了活性化合物的构效关系，通过结构优化，获得了8个高杀菌活性的化合物，有些化合物具有潜在的应用前景，有些可作为后续研究的先导化合物。通过本项目的研究发现：作为CYP51酶抑制剂应具有和Fe原子配位结合的结构单元，且在CYP51的活性位点可与相应的氨基酸残基形成氢键、π-π堆积等作用的特点。这为设计新型CYP51酶抑制剂提供了重要的实验基础和理论依据。其次，本项目首次利用BF3.OEt2和La(OTf)3 作催化剂来合成苯并噁嗪类化合物，为苯并噁嗪类化合物的合成提供了新方法。