New Quinolinyl–1,3,4–Oxadiazoles: Synthesis, In Vitro Antibacterial, Antifungal and Antituberculosis Studies
作者:Rahul V. Patel、Premlata Kumari、Kishor H. Chikhalia
DOI:10.2174/1573406411309040014
日期:2013.4.1
In order to generate hybrid antimicrobial remedies with novel mode of action, two series of quinoline based
1,3,4-oxadiazole derivatives condensed with N-aryl/benzothiazolyl acetamides were synthesized and the MIC values of
the compounds towards eight reference bacterial strains (S. aureus, B. cereus, E. coli, P. aeruginosa, K. pneumoniae, S.
typhi, P. vulgaris, S. flexneri), four fungi (A. niger, A. fumigatus, A. clavatus, C. albicans) and Mycobacterium tuberculosis
H37Rv were assayed in vitro. Quinoline–6–carboxlic acid was treated with thionyl chloride in refluxing methanol to
obtain the corresponding ester derivative to be hydrazinolyzed by 99% hydrazine hydrate in ethanol to produce carbohydrazide
intermediate. The carbohydrazide precursor underwent cyclization by carbon disulfide and ethanolic KOH to construct
5–quinolinyl–6–yl–1,3,4–oxadiazol–2–thiol. Substituted 2–chloro–N–phenyl(benzothiazolyl)aceta-mide derivatives
were then condensed to 1,3,4-oxadiazole nucleus via sulphur linkage to yield the desired products. Target products bearing
N–benzothiazolyl–2–chloroacetamides displayed good inhibitory potential. The biological screening identified that
many final analogues exhibited a significant inhibition of the growth of microorganisms at 3.12-25 μg/mL of MIC, which
were comparable to control drugs. The influence of the presence of various functional groups to the phenyl/benzothiazolyl
ring on activity profiles was investigated. The proposed structures of the newly prepared products were confirmed with
the aid of IR, 1H NMR, 13C NMR spectroscopy and elemental analysis. These results may provide new insights in the design
of a novel pool of bioactive templates.
为了产生具有新作用模式的混合抗菌药物,合成了两个系列的喹啉基 1,3,4-恶二唑衍生物与 N-芳基/苯并噻唑基乙酰胺缩合物。金黄色葡萄球菌、蜡样芽孢杆菌、大肠杆菌、铜绿假单胞菌、肺炎双球菌、伤寒杆菌、脓疱疮菌、柔毛杆菌)、四种真菌(黑木耳、烟曲霉、克拉维氏菌、白僵菌)和结核分枝杆菌 H37Rv 的 MIC 值进行了体外检测。在回流甲醇中用亚硫酰氯处理喹啉-6-甲酸,得到相应的酯衍生物,然后用 99% 的水合肼在乙醇中进行肼解,生成肼中间体。羧酰肼前体在二硫化碳和乙醇 KOH 的作用下发生环化反应,生成 5-喹啉基-6-基-1,3,4-恶二唑-2-硫醇。然后,取代的 2-氯-N-苯基(苯并噻唑基)乙酰胺衍生物通过硫键与 1,3,4-恶二唑核缩合,得到所需的产物。含有 N-苯并噻唑基-2-氯乙酰胺的目标产品显示出良好的抑制潜力。生物筛选结果表明,许多最终类似物在 3.12-25 μg/mL 的 MIC 值下对微生物的生长有明显的抑制作用,与对照药物相当。研究还探讨了苯基/苯并噻唑环上存在的各种官能团对活性的影响。红外光谱、1H NMR、13C NMR 光谱和元素分析证实了新制备产品的拟议结构。这些结果可为设计新型生物活性模板库提供新的见解。