Novel inhibitors of 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR)

描述（由申请人提供）：本提案的总体目标是使用传统药物化学和基于计算结构的药物设计的组合来开发1-脱氧-D-木酮糖-5-磷酸还原异构酶（DXR）的新型小分子抑制剂，并测试其对病原菌和寄生虫的体外生物活性。异戊二烯的生物合成对所有生物体都是必不可少的。人类使用甲羟戊酸途径产生异戊烯基二磷酸（IPP）和二甲基烯丙基二磷酸（DMAPP），这是所有类异戊二烯生物合成的两种常见前体;结核病，以及顶复门寄生虫，如恶性疟原虫和T.在弓形虫中，非甲羟戊酸途径用于制备IPP和DMAPP。由于人类缺乏非甲羟戊酸途径中的所有7种酶，因此它已成为抗感染药物发现的有吸引力的靶点。已发现磷咪霉素是该途径的唯一有效抑制剂，阻断第二种酶DXR，并且在最近的临床试验中具有针对许多革兰氏阴性细菌的抗菌活性和抗疟疾活性。然而，革兰氏阳性细菌（例如，M.结核）和一些革兰氏阴性细菌以及某些致病性寄生虫（例如，T.弓形虫）对磷霉素具有抗性。此外，其药代动力学特征较差，血浆半衰期为0.5-1.5 h。鉴于目前面临迅速上升的耐药性以及新的抗感染药物短缺的破坏性局势，迫切需要找到新的传染病武器。第一个具体目标是使用药物化学和基于计算结构的药物设计的组合来开发新型DXR抑制剂。基于合理的、基于结构的设计，我们发现了新的、药物样的先导抑制剂，其对重组大肠杆菌的Ki低至310 nM。coliDXR酶。我们的对接研究表明，他们可以结合DXR在不同的模式，从磷霉素。这些类药物化合物应该具有进一步开发的巨大潜力。我们建议：1）利用药物化学的方法，以先导化合物为骨架构建多个系列的化合物库，寻找活性更高的化合物; 2）对这些化合物进行QSAR研究; 3）获得DXR与我们的新型抑制剂复合物的X-射线晶体结构; 4）利用计算和晶体学研究的结果指导我们进一步的药物设计和合成。第二个具体目标是测试我们的抑制剂对广泛的细菌和顶复门寄生虫及其重组DXR酶的体外生物活性。最后，我们还将测试我们的强效DXR抑制剂对人类细胞系的细胞毒性，以评估其潜在毒性。 公共卫生相关性：拟议的研究旨在开发新的潜在疗法来治疗耐药性传染病。我们将专注于发现和开发新型化合物，这些化合物可以阻断细菌和疟疾寄生虫中特有的重要生物靶标。

DESCRIPTION (provided by applicant): The overall objectives of this proposal are to use a combination of traditional medicinal chemistry and computational, structure based drug design to develop novel small molecule inhibitors of 1-deoxy-D-xylulose-5- phosphate reductoisomerase (DXR) and test their in vitro biological activities on pathogenic bacteria and parasites. Isoprene biosynthesis is essential to all organisms. Humans use the mevalonate pathway to produce isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), two common precursors for all isoprenoid biosynthesis; however, in most pathogenic bacteria, such as P. aeruginosa and M. tuberculosis, as well as apicomplexan parasites, such as P. falciparum and T. gondii, the non-mevalonate pathway is used to make IPP and DMAPP. Since humans lack all the 7 enzymes in the non-mevalonate pathway, it has become an attractive target for anti-infective drug discovery. Fosmidomycin has been found to be the only potent inhibitor of this pathway, blocking DXR, the 2nd enzyme, and has antibacterial activity against many Gram- negative bacteria and antimalarial activity in recent clinical trials. However, Gram-positive bacteria (e.g., M. tuberculosis) and some Gram-negative bacteria as well as certain pathogenic parasites (e.g., T. gondii) are resistant to fosmidomycin. In addition, it has a poor pharmacokinetic profile with a half-life in plasma of 0.5-1.5 h. Given the current devastating situation facing quickly rising drug resistance as well as shortage of new anti- infective drugs, there is a pressing need to find new weaponry for infectious diseases. The first Specific Aim is to use a combination of medicinal chemistry and computational, structure based drug design to develop novel inhibitors of DXR. Based on rational, structure based design, we have found novel, drug-like lead inhibitors with Kis as low as 310 nM against a recombinant E. coli DXR enzyme. Our docking studies showed that they could bind to DXR in different modes from that of fosmidomycin. These drug-like compounds should have great potential for further development. We propose 1) to use medicinal chemistry to make several series of compound libraries based on the scaffolds of the lead inhibitors, in order to find compounds with improved activity; 2) to carry out QSAR studies of these compounds; 3) to obtain x-ray crystal structures of DXR in complex with our novel inhibitors; and 4) to use the results from the computational and crystallographic studies to guide our further drug design and synthesis. The second Specific Aim is to test in vitro biological activity of our inhibitors on a broad range of bacteria and apicomplexan parasites as well as their recombinant DXR enzymes. Finally, we will also test the cytotoxicity of our potent DXR inhibitors on human cell lines to evaluate their potential toxicity. PUBLIC HEALTH RELEVANCE: The research proposed is designed to lead to new potential therapeutics to treat drug-resistant infectious diseases. We will focus on the discovery and development of novel compounds that block essential biological targets that are exclusively found in bacteria and malaria parasites.