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种主要是对称的二胺中开发出来的。乙胺丁醇是一种用组合化学方法优化的理想小分子药物：毒性低，药代动力学好，但其MIC较高，为5 mg/ml，可通过添加类似物和药物化学来显著提高。我们设计了一种固相合成与乙胺丁醇相关的不对称1，2-二胺的方案，并使用该方案合成了一个包含100,000个结构类似物的测试库。用对细胞壁抑制反应积极的全细胞荧光素酶系统和微量肉汤稀释法对该文库进行筛选，以确定其对结核分枝杆菌的最低抑菌浓度。通过这个程序，我们得到了大约300个离散的命中结果，这些结果在两种检测中都显示了活性。我们建议扩大这个文库所代表的结构多样性，特别强调第一个文库中未被充分代表的分子类别，以及围绕可行的HITS进行额外的类比。药物化学将以SAR和肠道吸收的可能性为指导。我们提出了一系列的生化分析，使我们能够确定HIT分子的优先顺序，并确认这些分子共享一个共同的靶点，以便于解释SAR。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查系统，使我们能够将适当的热门系列向前推进到结核病的小动物模型中。这些研究应该能够让我们确定最终将接受人体疗效评估的候选药物。

Ethambutol (EMB) was developed at Lederle Laboratories in the late 1950s 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 MIC 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 MICs 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.