Second Generation Antibiotics from Ethambutol

乙胺丁醇（EMB）是20世纪50年代末在Lederle实验室从大约2000种大部分对称的二胺中开发出来的。乙胺丁醇是一种理想的小分子药物，它具有低毒性和良好的药代动力学，但相对较高的MIG为5 mg/ml，通过额外的类似物和药物化学可以显著改善。我们设计了一种与乙胺丁醇相关的不对称1,2 -二胺的固相合成方法，并使用该方法合成了100,000个结构类似物的测试库。该文库已使用全细胞荧光素酶系统进行筛选，该系统对细胞壁抑制反应积极，并使用微肉汤稀释法测定抗结核分枝杆菌的MIGs。从这个过程中，我们得到了大约300个在两种分析中都显示活性的离散点。我们建议扩展这个库所代表的结构多样性，特别强调在第一个库中代表性不足的分子类别，以及围绕可行的目标进行额外的模拟。药物化学将以SAR和肠吸收可能性为指导。我们提出了一系列生化分析，这将使我们能够优先考虑击中分子，并确认这些分子有一个共同的目标，以促进对SAR的解释。这些分析将扩展到包括相关铅系列的初步药理学和药代动力学分析。我们将进一步建立体内筛选系统，使我们能够将适当的打击系列推向结核病的小动物模型。这些研究将使我们能够确定候选药物，并最终评估其对人类的疗效。

Ethambutol (EMB) was developed at Lederle Laboratories in the late 1 950s from a collection of about 2000 mostly symmetrical diamines. Ethambutol is an ideal small-molecule drug to be optimized by combinatorial chemistry: it has low toxicity and good pharmacokinetics, but a relatively high MIG of 5 mg/ml that could be dramatically improved through additional analoging and medicinal chemistry. We have devised a protocol for solid-phase synthesis of asymmetric 1 ,2- diamines related to ethambutol and used this protocol to synthesize a test library of 100,000 structural analogs. This library has been screened using both a whole-cell luciferase system that responds positively to cell- wall inhibition and using microbroth dilution assays for the determination of MIGs against Mycobacterium tuberculosis. From this procedure we arrived at approximately 300 discrete hits that show activity in both assays. We propose to extend the structural diversity represented-by this library with particular emphasis on classes of molecules underrepresented in the first library as well as additional analoging around viable hits. Medicinal chemistry will be guided by both SAR and likelihood of intestinal absorption. We propose a series of biochemical analyses that will allow us to prioritize hit molecules and confirm that these molecules share a common target in order to facilitate interpretation of SAR. These assays will be extended to include preliminary pharmacologic and pharmacokinetic analysis of related lead series. We will further establish in vivo screening systems that will allow us to move appropriate hit series forward into small animal models of tuberculosis. These studies should allow us to identify candidates that will ultimately be evaluated for efficacy in humans.