Syntheses and evaluation of macrocyclic engelhardione analogs as antitubercular and antibacterial agents
作者:Li Shen、Marcus M Maddox、Sudip Adhikari、David F Bruhn、Manish Kumar、Robin E Lee、Julian G Hurdle、Richard E Lee、Dianqing Sun
DOI:10.1038/ja.2013.21
日期:2013.6
The natural product engelhardione is an underexplored chemotype for developing novel treatments for bacterial infections; we therefore explored this natural product scaffold for chemical diversification and structureâactivity relationship studies. Macrocyclic engelhardione and structural regioisomers were synthesized using a series of aldol condensations and selective hydrogenations to generate the 1,7-diarylheptan-3-one derivatives, followed by microwave-assisted intramolecular Ullmann coupling to afford a series of macrocyclic diaryl ether analogs. An extended macrocyclic chemical library was then produced by oxime formation, reductive amination and O-alkylation. Antibacterial evaluation revealed that the reductive amination derivatives 7b and 7d showed moderate activities (minimum inhibitory concentrations: 12.5â25âμgâmlâ1) against Mycobacterium tuberculosis and Gram-positive pathogens, as well as anti-Gram-negative activity against an efflux impaired Escherichia coli strain. These results provide validated leads for further optimization and development.
天然产物恩格尔哈酮是一种尚未充分开发的化学类型,可用于开发细菌感染的新疗法;因此,我们探索了这种天然产物的化学多样性,并对其结构-活性关系进行了研究。通过一系列醛缩合和选择性氢化反应,我们合成了大环恩格尔哈酮和结构区域异构体,生成1,7-二芳基庚烷-3-酮衍生物,然后通过微波辅助分子内乌尔曼偶联反应,得到一系列大环二芳基醚类似物。通过肟形成、还原胺化和O-烷基化反应,我们构建了一个扩展的大环化学库。抗菌评估显示,还原胺化衍生物7b和7d对结核分枝杆菌和革兰氏阳性病原体具有中等活性(最低抑菌浓度:12.5-25µg·ml-1),对一种外排受损的大肠杆菌菌株具有抗革兰氏阴性活性。这些结果为进一步优化和开发提供了有效的线索。