Nwuche Charles O, Ujam Oguejiofo T, Ibezim Akachukwu, Ujam Ifeoma B
Department of Microbiology, University of Nigeria, Nsukka, Enugu State, Nigeria.
Japan International Research Center for Agricultural Sciences (JIRCAS), Tsukuba, Ibaraki, Japan.
PLoS One. 2017 Jan 20;12(1):e0170150. doi: 10.1371/journal.pone.0170150. eCollection 2017.
The Antibiogram properties of 1-chloro-2-isocyanatoethane derivatives of thiomorpholine (CTC), piperazine (CPC) and morpholine (CMC) were evaluated by the approved agar well diffusion, the minimum inhibitory concentration (MIC) and in silico techniques. A total of fourteen microbial cultures consisting of ten bacteria and four yeast strains were used in the biological study while affinity of the compounds for DNA gyrase, a validated antibacterial drug target, was investigated by docking method. Results indicate that both thiomorpholine and piperazine had zero activity against the Gram negative organisms tested. With morpholine, similar result was obtained except that cultures of Escherichia coli (ATCC 15442) and Salmonella typhi (ATCC 6539) presented with weak sensitivity (7-8 mm) as shown by the inhibition zone diameter (IZD) measurement. The Gram positive organisms were more sensitive to morpholine than the other compounds. The highest IZD values of 15-18 mm were achieved except for Streptococcus pneumoniae (ATCC 49619) in which mobility of the compound stopped after 12 mm. S. pneumoniae was resistant to both thiomorpholine and piperazine. The yeast strains were not sensitive to any of the studied compounds investigated. The MIC tests evaluated against a reference antibiotic show that while morpholine was most active at 4 μg.ml-1 against both B. cereus ATCC (14579) and B. subtilis, the least active compound was thiomorpholine which inhibited S. aureus (ATCC 25923) at 64 μg.ml-1. The three compounds demonstrated high affinity for the target protein (DNA gyrase) ranging from -4.63 to -5.64 Kcal/mol and even showed better ligand efficiencies than three known antibiotics; chlorobiocin, ciprofloxacin and tetracycline. This study identified the studied compounds as potential antibiotic leads with acceptable physicochemical properties and gave the molecular basis for the observed interactions between the compounds and the target protein which can be harnessed in structural optimization process.
通过认可的琼脂孔扩散法、最低抑菌浓度（MIC）法以及计算机模拟技术，对硫代吗啉（CTC）、哌嗪（CPC）和吗啉（CMC）的1-氯-2-异氰酸酯乙烷衍生物的抗菌谱特性进行了评估。在生物学研究中总共使用了由10种细菌和4种酵母菌株组成的14种微生物培养物，同时通过对接方法研究了这些化合物对DNA回旋酶（一种经过验证的抗菌药物靶点）的亲和力。结果表明，硫代吗啉和哌嗪对所测试的革兰氏阴性菌均无活性。对于吗啉，除了大肠埃希菌（ATCC 15442）和伤寒沙门氏菌（ATCC 6539）的培养物表现出较弱的敏感性（抑菌圈直径为7 - 8毫米）外，得到了类似的结果。革兰氏阳性菌对吗啉比其他化合物更敏感。除了肺炎链球菌（ATCC 49619）外，最高抑菌圈直径值达到15 - 18毫米，在肺炎链球菌中化合物的扩散在12毫米后停止。肺炎链球菌对硫代吗啉和哌嗪均耐药。酵母菌株对所研究的任何化合物均不敏感。针对一种参考抗生素进行的MIC测试表明，吗啉对蜡样芽孢杆菌ATCC（14579）和枯草芽孢杆菌的活性最高，为4μg.ml-1，而活性最低的化合物是硫代吗啉，它在64μg.ml-1时抑制金黄色葡萄球菌（ATCC 25923）。这三种化合物对靶蛋白（DNA回旋酶）表现出高亲和力，范围为-4.63至-5.64千卡/摩尔，甚至比三种已知抗生素（氯生菌素、环丙沙星和四环素）表现出更好的配体效率。本研究确定所研究的化合物为具有可接受物理化学性质的潜在抗生素先导物，并为观察到的化合物与靶蛋白之间的相互作用提供了分子基础，这可用于结构优化过程。
