N-取代苯基-5-取代苯基-3H-1,2,4-三唑-3-硫酮衍生物的合成及抗菌活性研究

目的 以苯甲酸为原料，经4步反应合成一系列N-取代苯基-5-取代苯基-3H-1,2,4-三氮唑-3-硫酮化合物并研究其抗菌活性。方法 基于课题组前期对新型潜在三唑类抗菌化合物6h的作用机制研究，筛选多个侧链基团，使用乙醇和碳酸钠作溶剂改善最后一步反应条件，通过硅胶柱色谱分离纯化目标化合物，合成一系列1,2,4-三唑类化合物并采用质谱(MS)和1H NMR、13C NMR进行结构表征。通过琼脂扩散法初步筛选所有化合物对肺炎克雷伯菌、金黄色葡萄球菌和铜绿假单胞菌3种常见菌株的抗菌活性，并通过微量稀释法进一步测定它们的最小抑菌浓度(MIC值)。结果 合成17个含有卤代苯基和其他侧链基团的目标化合物，其MS以及核磁共振谱图数据表明所有化合物结构正确。抗菌活性初步筛选可知化合物6a、6b、6d、6f、6g、6h、6k、6m和6p等9个化合物具有不错的抑菌能力，其MIC测试结果表明，大部分化合物对所测菌株的MIC值在25~100μg/mL范围内。尤其是化合物6h和6k对肺炎克雷伯菌的MIC值达到25μg/mL，抑菌活性与对照药物氨苄西林相当。结论 在前期作用机制研究基础上，通过对构效关系的阐述，发现一些侧链片段如间位卤代苯基或对位卤代苯基、三氟甲基苯基等具有吸电子基团的苯基、吡啶基等对1,2,4-三唑类衍生物的抗菌活性有明显增强作用，证实侧链基团与受体蛋白形成特异性协调作用和氢键作用从而发挥衍生物的抗菌活性。

Synthesis and antimicrobial study of novel 4,5-disubstituted aryl-2,4-dihydro-3H-1,2,4-triazole-3-thoxone derivatives

Objective To synthesize a series of 4,5-disubstituted aryl-2,4-dihydro-3H-1,2,4-triazole-3-thione derivatives and study their antibacterial activity. Methods A novel triazole derivate antibacterial compound 6h was discovered as a lead compound. The binding capacity of the active site of 6h was further analyzed in detailwith the target protein by molecular docking experiments in silico. With the assistance of computer-aided design, multiple side chain fragments were high-throughput screened to select the optimal candidate with the triazole core. The 17 4,5-disubstituted aryl-2,4-dihydro-3H-1,2,4-triazole-3-thoxone derivatives were designed and synthesized, together with the characterization by 1H NMR, 13C NMR, and mass spectrometry. The antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae was determined by the microdilution method. Results The MS and NMR spectra data of the compounds indicated that the newly synthesized compounds were structurally correct. The nine compounds (6a, 6b, 6d, 6f, 6g, 6h, 6k, 6m and 6p) initially screened have antibacterial ability. The MIC values of the above compounds were further tested, and the results showed that most of the compounds of MIC value were in the range of 25~100μg/mL. In particular, the MIC values of compounds 6h and 6k against Klebsiella pneumoniae reached 25μg/mL, and the antibacterial activity was comparable to that of the control drug ampicillin. Conclusion A detailed analysis of the structure-activity relationship revealed that some side chain fragments, such as meta or para substituted phenyl, electron-withdrawing trifluoromethyl phenyl, nitrogen-containing pyridine have significant effects on improving the antimicrobial activity of 1,2,4-triazole