Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck College, University of London, London WC1E 7HX, UK.
J Antimicrob Chemother. 2010 Oct;65(10):2101-7. doi: 10.1093/jac/dkq313. Epub 2010 Aug 18.
New anti-mycobacterial entities with novel mechanisms of action are clinically needed for treating resistant forms of tuberculosis. The purpose of this study was to evaluate anti-tubercular activity and selectivity of seven recently isolated natural products from Colombian plants.
MICs were determined using a liquid medium growth inhibition assay for Mycobacterium tuberculosis H(37)Rv and both solid and liquid media growth inhibition assays for Mycobacterium bovis BCG. Escherichia coli growth inhibition and mammalian macrophage cell toxicity were evaluated to establish the degree of selectivity of the natural product against whole cell organisms. Enzymatic inhibition of ATP-dependent MurE ligase from M. tuberculosis was assayed using a colorimetric phosphate detection method. The most active compound, 3-methoxynordomesticine hydrochloride, was further investigated on M. bovis BCG for its inhibition of sigmoidal growth, acid-fast staining and viability counting analysis.
Aporphine alkaloids were found to be potent inhibitors of slow-growing mycobacterial pathogens showing favourable selectivity and cytotoxicity. In terms of their endogenous action, the aporphine alkaloids were found inhibitory to M. tuberculosis ATP-dependent MurE ligase at micromolar concentrations. A significantly low MIC was detected for 3-methoxynordomesticine hydrochloride against both M. bovis BCG and M. tuberculosis H(37)Rv.
Considering all the data, 3-methoxynordomesticine hydrochloride was found to be a potent anti-tubercular compound with a favourable specificity profile. The alkaloid showed MurE inhibition and is considered an initial hit for exploring related chemical space.
对于治疗耐药性肺结核，临床上需要具有新型作用机制的新型抗分枝杆菌药物。本研究的目的是评估七种从哥伦比亚植物中分离出的新型天然产物的抗结核活性和选择性。
使用液体培养基生长抑制法测定结核分枝杆菌 H（37）Rv 的 MIC，使用固体和液体培养基生长抑制法测定牛分枝杆菌 BCG 的 MIC。评估大肠杆菌生长抑制和哺乳动物巨噬细胞毒性，以确定天然产物对全细胞生物的选择性程度。使用比色磷酸检测法测定结核分枝杆菌 ATP 依赖性 MurE 连接酶的酶抑制作用。最活跃的化合物 3-甲氧基诺多丁胺盐酸盐进一步用于牛分枝杆菌 BCG 的研究，以抑制其对数生长期生长、抗酸性染色和存活计数分析。
阿朴啡生物碱被发现是强效的慢生长分枝杆菌病原体抑制剂，具有良好的选择性和细胞毒性。就其内在作用而言，阿朴啡生物碱在微摩尔浓度下对结核分枝杆菌 ATP 依赖性 MurE 连接酶具有抑制作用。3-甲氧基诺多丁胺盐酸盐对牛分枝杆菌 BCG 和结核分枝杆菌 H（37）Rv 的 MIC 均显著降低。
综合所有数据，3-甲氧基诺多丁胺盐酸盐是一种具有良好特异性的有效抗结核化合物。该生物碱具有 MurE 抑制作用，被认为是探索相关化学空间的初始命中。
