MDR-TB Drugs: Targeting Cell Wall Synthetic Enzymes

描述(由申请人提供)：NIH通知NOT-AI-02-023的一个目的是加速导致治疗耐多药结核病的研究，MDR-TB是一种潜在的生物恐怖主义制剂。需要基于与目前的结核病药物不同的靶点的新的化疗药物，但准备用于临床试验的所需的先导化合物很少。针对缺乏所需的先导化合物，有人提议通过开发几种目前药物没有靶向的基本细胞壁合成酶的抑制剂来开发新的先导药物，这些先导药物对耐多药结核病具有活性，并在小鼠中有效。 通过用微量平板酶分析筛选化学文库，已鉴定出抑制三种不同细胞壁合成酶的化合物(其中一些还抑制结核杆菌的生长)。这些和类似识别的HITS将被提炼成高效的酶抑制剂，也可以使用“复合提纯”周期来对抗耐多药结核病。该周期从“化合物开发小组”对目标酶(特别是带有键抑制剂的酶)进行X射线结晶学研究开始，然后进行分子建模以设计新的抑制剂，最后在此模型的基础上合成一组化合物，并纳入化学多样性。然后，“化合物分析小组”确定酶抑制的效果、一组耐多药结核病分离株的MIC值、体外细胞毒性以及对小鼠的毒性、干扰素-γ基因敲除小鼠的有效性、基本药代动力学和标准小鼠模型的有效性。将化合物分析组的数据传递给化合物开发组，以便制备新一轮的进一步精制化合物。对每一类抑制剂继续进行这个循环，直到出现具有所需性质的化合物，或者确定某一类化合物不太可能产生新药。目前已经准备好从三种基本酶的抑制剂开始这个周期；此外，我们还将开发微量平板分析方法，并为另外四种基本细胞壁生物合成酶的HITS筛选化学库，这些酶将进入精制周期。

DESCRIPTION (provided by applicant): A purpose of NIH Notice NOT-AI-02-023 is to expedite research leading to the treatment of MDR-TB, a potential bioterrorism agent. New chemotherapies based on different targets than the present TB drugs are needed, but there is a paucity of the required leads ready for clinical trials. In response to this lack of required leads, it is proposed to develop new leads active against MDR-TB and effective in mice by developing inhibitors of several essential cell wall synthetic enzymes not targeted by current drugs. Compounds that inhibit three different cell wall synthetic enzymes (some of which also inhibit the growth of TB) have been identified by screening a chemical library with microtiter plate based enzyme assays. These and similarly identified hits will be refined into highly effective enzyme inhibitors also active against MDR-TB using a "compound refinement" cycle. The cycle begins with the "compound development group" doing X-ray crystallography studies of the targeted enzymes (especially enzymes with bond inhibitors), proceeding to molecular modeling to design new inhibitors and finally synthesizing a group of compounds based on this modeling and also incorporating chemical diversity. Then the "compound analysis group" determines efficacy of enzyme inhibition, MIC values on a panel of MDR-TB isolates, in vitro cell toxicity, and as warranted, toxicity in mice, efficacy in an interferon gamma knock out mouse, basic pharmacokinetics, and efficacy in a standard mouse model. The data from the compound analysis group is relayed to the compound development group so that a new round of further refined compounds can be prepared. The cycle is continued for each class of inhibitors until compounds with the desired properties emerge or it is determined that a particular class of compounds is unlikely to be yield new drugs. The cycle is presently ready to begin with inhibitors of three essential enzymes; in addition we will develop microtiter plate assays and screen chemical libraries for hits for four additional essential cell wall biosynthetic enzymes which will then enter the refinement cycle.