含取代苯肼的tetramic acid先导物的结构优化、杀菌活性及3D-QSAR研究

This research subject intends to optimize the molecular structures of leading compounds tetramic acids incorporating the moiety of substituted phenylhydrazines, which embodies the original innovation, for screening novel green fungicides which can effectively prevent the fungal diseases of crops. The microbial metabolite tenuazonic acid has a variety of biological activities, by modifying its structure, the derivatives pyrrolidinediones containing substituted phenylhydrazine were found having significant inhibitory activity against wheat scab (Fusarium gramineaum) and other plant pathogens, and no cross resistance to carbendazim. The secondary leading compound was planed to be optimized under the guidance of the bioisostere principle and the similar synthesis method. These modifying would be focused on 2-nitrogen atom of hydrazine group and the pyrrole ring. Two-halogenated pyrazole or fluorinated methyl pyrazole derivatives which containing substituted phenylhydrazine, phenyl acylhydrazide, phenyl amide and phenyl amine moiety would be designed and synthesized for improving the fungicidal activity and heightening the structure stability. Moreover, through the fungicidal activity screening and analysis of 3D-QSAR, the CoMFA and CoMSIA model would be established to simulate the molecular interaction, the target molecules would be further optimized, and the excellent compounds would be carried out the field efficacy and acute toxicity test. We expect to obtain one or two new candidate compounds possessing independent intellectual property rights and good properties of high efficiency, low toxicity and good environmental compatibility, which could be recommended to enter the development stage of candidate pesticides. The designed novel molecular scaffolds using as new fungicides to research and develop is a useful attempt, could provide new and effective control techniques against plant diseases.

本项目拟对具有原始创新的先导物进行结构优化，筛选能有效防治作物真菌病害的新型绿色杀菌剂。经对天然产物tenuazonic acid进行结构修饰，发现含取代苯肼的吡咯烷二酮化合物对小麦赤霉病菌等植物病原菌具有显著的抑制活性，且与多菌灵无交互抗性。拟在生物电子等排原理和类同合成法指导下，对二次先导物进行优化设计，重点对肼基的2位氮原子和吡咯环进行修饰，合成含取代苯肼、取代苯基酰肼、取代苯基酰胺和取代苯胺基团的二卤代吡唑及氟代甲基吡唑类衍生物，提高先导物的杀菌活性与结构稳定性。同时，通过3D-QSAR构效关系分析，建立CoMFA和CoMSIA模拟分子作用模型，对目标分子结构进行再优化，并对其中优异者进行急性毒性与田间小区药效试验，力争筛选到1-2个具有自主知识产权的高效、低毒、环境相容性好的候选化合物。本项目设计的化合物分子骨架新颖，作为杀菌剂创制是一有益尝试，可为作物病害防治提供新的有效手段。

以含取代苯肼基团的吡咯烷-2,4-二酮为先导，以生物电子等排原理和类同合成法为指导，借助计算机辅助分子设计方法，设计并合成了12大类共计480个结构新颖的目标化合物，包括氯代吡唑甲醛苯腙和氯代吡唑甲酰苯肼、含有喹唑啉酮结构的乙酰苯肼、含噻二嗪硫酮结构的酰胺和酰肼、含二苯醚基团的肼基吡咯烷二酮和含二苯醚基团的吡唑甲酰肼、含三氟甲基吡唑基团的乙酰胺及乙酰肼、含有苯并咪唑基团的酰胺、含苯并咪唑和苯基吡唑的酰胺、噻唑酰肼、含苯并噻唑基团的吡唑酰肼、吡唑磺酰肼、含有噻唑、呋喃或噻吩环的氟代甲基吡唑酰胺及含有肟醚尾链的吡唑酰胺。采用1H-NMR、13C-NMR、19F-NMR、FT-IR、HR-MS及X-射线单晶衍射分析确证了目标化合物的分子结构。.测定了目标化合物对5种植物病原真菌的抑制活性，有8类化合物对水稻纹枯病菌显示了突出的杀菌活性，其中化合物A29、C24、C27、F15、K15、K19、K27、K32和L21的EC50值分别达到0.15、0.15、0.12、0.14、0.09、0.10、0.13、0.15和0.15 μg/mL，优于多菌灵等对照药剂。有3类化合物对小麦赤霉病菌显示出良好的抑制效果，其中化合物F13、K6、K7、K16、K26和K27的EC50值分别达到0.27、0.26、0.25、0.20、0.28和0.12 μg/mL，优于多菌灵等对照药剂。有2类化合物对草莓灰霉病菌具有显著的抑制活性，其中化合物F7、N38和N44的EC50值分别为0.52、0.44和0.48 μg/mL，与啶酰菌胺相当。.对8个高活性化合物进行了活体药效试验。在200 μg/mL剂量下，化合物F15对水稻叶片上的纹枯病的保护性防效为73.25%，优于对照药剂多菌灵；化合物M57对盆栽水稻纹枯病具有75.76%的保护性防效，优于氟唑菌酰胺；化合物N38和N44对活体番茄灰霉病的防效分别达到62.06%和64.42%，与啶酰菌胺相当。.分析了10类化合物的分子结构与抑菌活性之间的3D-QSAR构效关系，构建的CoMFA模型和CoMSIA模型均具有良好的稳健性和预报能力，对目标化合物的结构优化具有重要指导意义。.采用分子对接、靶标酶抑制活性测定、扫描电镜和透射电镜观察菌丝形态和细胞超微结构、细胞膜通透性测定或荧光猝灭等实验手段，对7个高活性化合物的靶标酶及抑菌作用机制开展了探索研究。