N-Thiolated Beta-Lactams

N-硫醇化β-内酰胺

基本信息

批准号：
6622863
负责人：
EDWARD TUROS
金额：
$ 32.63万
依托单位：
UNIVERSITY OF SOUTH FLORIDA
依托单位国家：
美国
项目类别：
财政年份：
2002
资助国家：
美国
起止时间：
2002-03-01 至 2007-02-28
项目状态：
已结题

项目摘要

This project focuses on a very challenging problem in the medical community, the development of treatments for drug- resistant bacterial infections. The leading cause of clinical complications in the United States is nocosomial infections caused by the drug-resistant pathogen, Staphylococcus aureus. There is currently a dire need for new drugs to be developed for controlling these infections. Towards this goal, our proposal discusses efforts to identify the biochemical and chemical basis for antibacterial activity of N-thiolated beta-lactams, a new class of antibiotics discovered in our laboratory at University of South Florida. Preliminary data on more than 50 active analogues indicates that these substances possess antimicrobial behavior selective for Staphylococcus bacteria, with enhanced activity towards multi-drug resistant strains (MRSA). Unlike all previously known beta-lactam drugs, these compounds appear to affect early developmental events during cell replication, not cell wall crosslinking. These compounds have highly unusual structure-activity profiles which need to be explored further. Electron microscopy experiments indicate that our lactams produce no morphological defects in MRSA cells, or cytotoxic effects in human fibroblasts. The compounds are stable over a wide pH range (pH 1 to 10), and are totally transparent to penicillinases as well as to most chemical reagents we have studied. Our Proposed Studies consist of three Specific Aims. Aim 1 is to study the biochemical and chemical basis for antimicrobial activity, and will include (1) electron microscopy experiments to look for morphological defects in bacterial cells due to damage by the lactams, and to identify where the drug accumulates in the cell, (2) radiolabeling to determine which of the primary cellular processes (cell wall synthesis, protein synthesis, or nucleic acid synthesis) are affected by the beta-lactams, and the means by which the drugs function chemically, and (3) studies to define whether the lactams bind covalently or non-covalently to the biological target, and to identify the cellular target. Aim 2 is to assess further whether the lactams are cytotoxic to mammalian cells. Aim 3 is to develop new approaches to solid phase synthesis of affinity resins (for experiments on isolating the cellular target) and lactam libraries (for expanded drug screening). We also aim to develop novel prodrug delivery systems for the prevention and treatment of MRSA infections. We believe that these studies will provide extraordinary opportunities to develop new therapeutics and approaches for the control of hospital-borne drug-resistant infections.

该项目重点关注医学界一个非常具有挑战性的问题，即开发耐药细菌感染的治疗方法。在美国，临床并发症的主要原因是由耐药病原体金黄色葡萄球菌引起的医院感染。目前迫切需要开发新药来控制这些感染。为了实现这一目标，我们的提案讨论了确定 N-硫醇化 β-内酰胺抗菌活性的生化和化学基础的努力，N-硫醇化 β-内酰胺是我们在南佛罗里达大学实验室发现的一类新型抗生素。超过 50 种活性类似物的初步数据表明，这些物质对葡萄球菌具有选择性抗菌行为，并且对多重耐药菌株 (MRSA) 具有增强的活性。与所有先前已知的 β-内酰胺药物不同，这些化合物似乎影响细胞复制过程中的早期发育事件，而不是细胞壁交联。这些化合物具有非常不寻常的结构活性特征，需要进一步探索。电子显微镜实验表明，我们的内酰胺不会在 MRSA 细胞中产生形态缺陷，也不会在人成纤维细胞中产生细胞毒性作用。这些化合物在较宽的 pH 范围（pH 1 至 10）内稳定，并且对青霉素酶以及我们研究的大多数化学试剂完全透明。我们提出的研究包括三个具体目标。目标 1 是研究抗菌活性的生化和化学基础，包括 (1) 电子显微镜实验，以寻找由于内酰胺损伤而导致的细菌细胞形态缺陷，并确定药物在细胞中积聚的位置，（ 2) 放射性标记以确定哪些主要细胞过程（细胞壁合成、蛋白质合成或核酸合成）受到 β-内酰胺的影响，以及药物发挥化学作用的方式，以及 (3) 研究以确定是否内酰胺类与生物靶标共价或非共价结合，并鉴定细胞靶标。目标 2 是进一步评估内酰胺是否对哺乳动物细胞具有细胞毒性。目标 3 是开发固相合成亲和树脂（用于分离细胞靶标的实验）和内酰胺库（用于扩大药物筛选）的新方法。我们还致力于开发新型前药递送系统来预防和治疗 MRSA 感染。我们相信，这些研究将为开发新的疗法和方法来控制医院传播的耐药感染提供非凡的机会。