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Development Of New Chemotherapeutics For Tuberculosis

结核病新化疗药物的开发

基本信息

批准号：
7732501
负责人：
Clifton Barry
金额：
$ 128.85万
依托单位：
NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
依托单位国家：
美国
项目类别：
财政年份：
资助国家：
美国
起止时间：
至
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/7732501
关键词：
Active Sites Anabolism Animal Model Animals Anti-Bacterial Agents Antibiotic Therapy Area Bacteria Bacterial Typing Binding Biochemical Biological Biological Assay Biological Factors Biology Carbon Cell Wall Chemicals Chemistry Class Clavulanic Acid Clavulanic Acids Coenzymes Collaborations Collection Complex Computing Methodologies Development Drug Design Drug effect disorder Enzymatic Biochemistry Enzyme Inhibitor Drugs Enzyme Inhibitors Enzymes Equus caballus Evaluation Family Family member Fatty Acids Fatty-acid synthase Foundations Genomics Genus Mycobacterium Goals Growth Human Infection Institutes Iron Laboratories Lead Medicine Metabolic Minnesota Modeling Molecular Target Molecular Weight Mycobacterium tuberculosis Mycolic Acid NAD synthase Niacinamide Nitric Oxide Nitroimidazoles Nocardia Pathway interactions Penicillins Peptidyltransferase Pharmaceutical Preparations Phase II Clinical Trials Preclinical Testing Process Proteins Publications Quantitative Structure-Activity Relationship Role Running Science Scientist Series Siderophores Soil Solubility Staging Structure Synthesis Chemistry System Testing Thinking Triclosan Tropical Disease Tuberculosis United States National Institutes of Health Work analog base beta-Lactam Resistance beta-Lactamase cell envelope chemical synthesis college concept design drug development drug mechanism fatty acid metabolism fatty acid synthase II functional group high throughput screening hydroxy fatty acid in vivo inhibitor/antagonist interest isoniazid mycobacterial mycobactins novel pathogen practical application pre-clinical preclinical study programs thiolactomycin tool tuberculosis treatment

项目摘要

Currently this project focusses on five key areas: (1) the chemical synthesis of derivatives of a natural product called thiolactomycin that targets an enzyme involved in the biosynthesis of the mycobacterial cell wall, (2) the chemical synthesis of analogs of nitroimidazoles such as PA-824, (3) the synthesis and evaluation of inhibitors of synthesis of the mycobacterial siderophore, Mycobactin, (4) the synthesis and evaluation of substrates for, and inhibitors of, transpeptidases that are responsible for remodeling the TB cell envelope, and (5) the synthesis of inhibitors of NAD synthetase. Project (1) targets mycolic acids which are complex alpha-branched, beta-hydroxy fatty acids that are unique to mycobacteria which are heavily modified by a variety of functional groups. Mycolic acids are biosynthetically produced through an extension of normal fatty acid metabolism. In mycobacteria this is initiated by a "eukaryotic"-like Type I fatty acid synthase, a large multifunctional enzyme that produces primarily short-chain (16-24 carbons) fatty acids that are then substrates for a second fatty acid synthase system that is more typically associated with bacteria. This Type II system appears to be the molecular target for isoniazid as well as other inhibitors such as triclosan. Thiolactomycin is a low molecular weight natural product isolated from a soil Nocardia species that specifically inhibits one component of the bacterial Type II fatty acid synthase system. Although it is a modest inhibitor against most bacteria it has shown in vivo activity in various experimental infections of animals. Studies this year, however, have uncovered some serious metabolic stability issues with the core thiolactone ring that have resulted in termination of this series of molecules. In Project (2) we are synthesizing analogs of nitroimiadazooxazines and nitroimidazooxazoles related to PA-824. PA-824 is currently in Phase II studies in humans for the treatment of tuberculosis. Working with scientists at the Novartis Institute for Tropical Diseases, TBRS scientists have synthesized and characterized a large collection of analogs of these compounds and are advancing these through preclinical studies. Two candidate molecules were identified this year using computational methods (QSAR modeling) and were synthesized and found to be extremely potent (fourty fold better than PA-824) with improvements noted in solubility and toxicological profiling. These are currently in advanced preclinical testing and may advance to IND-enabling preclinical studies within the first quarter of 2009. In addition the enzyme responsible for activating these drugs has been conclusively identified and the mechanism of the drug class has been established. In this work we established the mechanism of action of PA-824 by synthesis of analogs and metabolites and in the process discovered an entire new family of enzymes and an entirely novel and unexpected chemical mechanism of drug action. These agents function as "Trojan horses" and intracellularly release Nitric oxide (NO) after activation by a bacterial enzyme. NO is a molecule intimately involved in natural human defense against tuberculosis and many other pathogens and this project suggests a new general paradigm for antibacterials development, as a result this work was just accepted for publication in Science. There are also immediate practical applications, in collaboration with scientists at the Genomics Institute of the Novartis Foundation (GNF) who have reengineered this protein into a soluble form we hope to have preliminary crystals that diffract x-rays for structural work. We have synthesized the deazaflavin cofactor of this enzyme in mg quantities (a 14 step synthesis) for cocrystalization studies and hope to initiate structure-guided synthesis of analogs this year. In Project (3) we are evaluating approaches to the inhibition of the biosynthesis of the iron-acquiring siderophore of Mycobacterium tuberculosis, Mycobactin. In collaboration with scientists at the Unvieristy of Minnesota's Center for Drug Design we are testing inhibitors of one of the earliest biosynthetic steps in this biosynthetic pathway. Targettinng iron acquisition builds upon a strong historical interest in TBRS in understanding the biosynthesis of this molecule which is required for bacterial growth during infection. we have designed and synthesized many analogs and several are being tested in animal models presently. In project (4) we are exploring the biological role of a unique family of L,D-transpeptidases that are thought to contribute to the inherent beta-lactam resistance of TB. By a combination of biochemical and chemical studies we have established the function of two of the five members of this family and we have synthesized a panel of inhibitors and substrates in the hopes of both elucidating the underlying biology/enzymology as well as developing proof of concept molecules for a TB-specific family of penicillin-like compounds. Working with scientists at the Albert Einstein College of medicine who have solved the x-ray Crystal structure of the TB Beta lactamase in complex with clavulanic acid we have now also initiated a structure-guided program for designing better inhibitors. In project (5) we are working with the Gerratana laboratory who have solved the x-ray crystal structure of NadE which performs the last step of Nicotinamide biosynthesis to design and synthesize inhibitors of this enzyme. Both computation and structure-based approaches are being applies to elaborate fragments bound at the enzyme active site. In addition a high-throughput screening assay for this enzyme has been designed and implemented together with the NIH Chemical Genomics Center and will be run this year.

目前，该项目侧重于五个关键领域：（1）称为硫乳霉素的天然产物的衍生物的化学合成，其靶向参与分枝杆菌细胞壁生物合成的酶，（2）硝基咪唑类似物如PA-824的化学合成，（3）分枝杆菌铁载体合成抑制剂，分枝杆菌素的合成和评价，（4）负责重塑TB细胞包膜的转肽酶的底物和抑制剂的合成和评价，和（5）NAD合成酶抑制剂的合成。项目（1）针对分枝菌酸，分枝菌酸是复杂的α-分支的β-羟基脂肪酸，其是分枝杆菌所特有的，被各种官能团大量修饰。分枝菌酸是通过正常脂肪酸代谢的扩展生物合成产生的。在分枝杆菌中，这是由“真核”样I型脂肪酸合酶启动的，I型脂肪酸合酶是一种主要产生短链（16-24个碳）脂肪酸的大型多功能酶，然后短链脂肪酸是更典型地与细菌相关的第二脂肪酸合酶系统的底物。该II型系统似乎是异烟肼以及其他抑制剂（如三氯生）的分子靶点。硫代乳霉素是一种低分子量的天然产物，分离自土壤诺卡氏菌属物种，特异性抑制细菌II型脂肪酸合成酶系统的一种组分。虽然它是一种针对大多数细菌的适度抑制剂，但它在各种动物实验感染中显示出体内活性。然而，今年的研究发现了核心硫内酯环的一些严重的代谢稳定性问题，这些问题导致了这一系列分子的终止。在项目（2）中，我们正在合成与PA-824相关的硝基咪唑并恶嗪和硝基咪唑并恶唑的类似物。PA-824目前正处于人类治疗结核病的II期研究中。TBRS科学家与诺华热带疾病研究所的科学家合作，合成并表征了大量这些化合物的类似物，并正在通过临床前研究推进这些类似物。今年使用计算方法（QSAR建模）确定了两种候选分子，并进行了合成，发现其非常有效（比PA-824好40倍），在溶解度和毒理学特征方面有所改善。这些药物目前正在进行高级临床前试验，并可能在2009年第一季度进入IND临床前研究。此外，负责激活这些药物的酶已被最终确定，并建立了药物类别的机制。在这项工作中，我们通过合成类似物和代谢物建立了PA-824的作用机制，并在此过程中发现了一个全新的酶家族和一种全新的、意想不到的药物作用化学机制。这些试剂起“特洛伊木马”的作用，并在被细菌酶激活后在细胞内释放一氧化氮（NO）。NO是一种与人类对结核病和许多其他病原体的自然防御密切相关的分子，该项目为抗菌药物的开发提供了一种新的一般范式，因此这项工作刚刚被《科学》杂志接受发表。与诺华基金会（GNF）基因组学研究所的科学家合作，也有直接的实际应用，他们将这种蛋白质重新设计成可溶性形式，我们希望有初步的晶体，可以吸收X射线进行结构工作。我们已经合成了这种酶的去氮黄素辅因子mg量（14步合成）共结晶研究，并希望今年开始类似物的结构指导合成。在项目（3）中，我们正在评估抑制结核分枝杆菌铁载体（Mycobactin）生物合成的方法。我们与明尼苏达大学药物设计中心的科学家合作，正在测试这种生物合成途径中最早的生物合成步骤之一的抑制剂。靶向铁的获取建立在对TBRS的强烈历史兴趣的基础上，以了解这种分子的生物合成，这是感染期间细菌生长所需的。我们已经设计和合成了许多类似物，目前有几种正在动物模型中进行测试。在项目（4）中，我们正在探索一个独特的L，D-转肽酶家族的生物学作用，该家族被认为有助于结核病的固有β-内酰胺耐药性。通过生物化学和化学研究的结合，我们已经建立了这个家族的五个成员中的两个的功能，并且我们合成了一组抑制剂和底物，希望阐明潜在的生物学/酶学以及开发TB特异性青霉素样化合物家族的概念分子的证据。与阿尔伯特·爱因斯坦医学院的科学家合作，他们已经解决了结核病β内酰胺酶与克拉维酸复合物的X射线晶体结构，我们现在也开始了一个结构指导的计划，以设计更好的抑制剂。在项目（5）中，我们正在与Gerratana实验室合作，他们已经解决了NadE的X射线晶体结构，NadE执行烟酰胺生物合成的最后一步，以设计和合成这种酶的抑制剂。计算和基于结构的方法都被应用于酶活性位点结合的精细片段。此外，已经与NIH化学基因组学中心一起设计并实施了这种酶的高通量筛选测定，并将于今年运行。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

SYNTHESIS AND SPECTROSCOPIC DIFFERENTIATION OF 2- AND 4-ALKOXYTHIOTETRONIC ACIDS.

2- 和 4- 烷氧基硫代四酮酸的合成和光谱区分。

DOI：
10.3987/com-03-9947
发表时间：
2004
期刊：
Heterocycles
影响因子：
0.6
作者：
Shenoy,Gautham;Kim,Pilho;Goodwin,Michael;Nguyen,Quynh-Anh;Barry,CliftonE;Dowd,CynthiaS
通讯作者：
Dowd,CynthiaS

Cell wall structure of a mutant of Mycobacterium smegmatis defective in the biosynthesis of mycolic acids.

分枝杆菌酸生物合成缺陷的突变体的细胞壁结构。