Synthesis of Novel Quinolone and Coumarin Based 1,3,4-Thiadiazolyl and 1,3,4-Oxadiazolyl N-Mannich Bases as Potential Antimicrobials
作者:Rahul V. Patel、Jigar K. Patel、Premlata Kumari、Kishor H. Chikhalia
DOI:10.2174/157017812802139681
日期:2012.7.1
Two series of 1,3,4-thiadiazole and 1,3,4-oxadiazole derivatives have been synthesized and characterized by
elemental and spectral (IR, 1H-NMR) data. The hydrazide derivatives of 4-hydroxy quinolone and coumarin moiety were
refluxed in carbon disulfide in ethanolic potassium hydroxide to obtain the corresponding hydrazinecarbodithioate salts
which were then treated in two ways with (i) sulfuric acid and (ii) hydrochloric acid at cooled temperature to furnish the
corresponding 1,3,4-thiadiazole and 1,3,4-oxadiazole intermediates, respectively, which were then treated with piperazine
bases in the presence of formalin in methanol to furnish the final N-Mannich products 7i-10vi. The newer analogs were
examined for their antimicrobial activity against five bacteria (S. aureus and B. cereus, E. coli, P. aeruginosa and K.
pneumoniae) and two fungi (A. niger and C. albicans) and the results revealed that compounds demonstrated excellent activity
(MICs: 3.12-25 μg/mL) as compared with the standards (MICs: 6.25-25 μg/mL).
合成并表征了两系列的1,3,4-噻二唑和1,3,4-呋喃二唑衍生物,使用了元素分析和谱学数据(红外光谱、1H-NMR)。将4-羟基喹啉和香豆素部分的肼酰胺衍生物在含有乙醇的氢氧化钾的碳二硫化物中回流,以获得相应的肼甲基二硫酸盐。随后,将其以两种方式处理:(i) 硫酸和 (ii) 盐酸,均在低温下进行,分别得到相应的1,3,4-噻二唑和1,3,4-呋喃二唑中间体。这些中间体再与哌嗪碱基在甲醇中与福尔malin反应,最终合成N-曼尼赫产物7i-10vi。这些新型类似物的抗微生物活性被测试,针对五种细菌(葡萄球菌、蜡样芽孢杆菌、大肠杆菌、铜绿假单胞菌和肺炎克雷伯菌)和两种真菌(黑曲霉和白念珠菌),结果显示这些化合物表现出很好的活性(最低抑菌浓度:3.12-25 μg/mL),相比标准(最低抑菌浓度:6.25-25 μg/mL)。