Propargyl-linked Antifolates Targeting Klebsiella pneumoniae

由肠杆菌科引起的感染，主要是革兰氏阴性病原体克雷伯氏菌 肺炎和大肠杆菌，正变得越来越难以治疗，由于 对包括青霉素，头孢菌素， 碳青霉烯类、氟喹诺酮类和抗叶酸剂。沿着阻力，自然有限的阵列 有效对抗革兰氏阴性病原体的药物的缺乏和抗生素发现的缺乏， 制药工业联合收割机产生了对新药发现的迫切需要。为 在过去的几年里，我们使用了基于结构的努力，开发了一系列新颖的 有效抑制必需酶二氢叶酸还原酶的炔丙基连接的抗叶酸剂 （DHFR），并且对革兰氏阳性和真核病原体有效。此外，这些 化合物显示出低的抗性率并具有良好的物理化学性质。最近， 我们已经发现炔丙基连接的抗叶酸剂是K.肺炎 在文化和反对K。肺炎DHFR。在这里，我们建议扩展这类 抗叶酸剂成为对抗致病性肠杆菌科的优良抗生素。我们提出 三个具体目标。在第一个目标中，我们将开发有效和选择性的抑制剂 抑制剂K. pneumoniae和E.大肠杆菌DHFR和野生型和抗性的有效抑制剂 肠杆菌科，如甲氧苄啶-、ESBL-、KPC-和NDM 1-变体，同时维持 低人体细胞毒性。在第二个目标，我们将确定迭代晶体结构的野生- 型和甲氧苄啶耐药肠杆菌科DHFR以及人DHFR，预期 来设计有效的和有选择性的化合物。第三个目标将侧重于研究 动物：一组有效化合物的初始阶段始于功效评估 针对野生型菌株和初始药代动力学参数。第二阶段将评估 对一系列表型的疗效沿着详细的药代动力学/药效学 参数在这个提案的最后，我们希望提供一个高效的，口服的 抗叶酸抗生素对广泛的肠杆菌科菌株。

Infections caused by Enterobacteriaceae, primarily the Gram-negative pathogens Klebsiella pneumoniae and Escherichia coli, are becoming increasingly difficult to treat owing to widespread resistance to several classes of antibiotics including penicillins, cephalosporins, carbapenems, fluoroquinolones and antifolates. Along with resistance, the naturally limited array of agents effective against Gram-negative pathogens and the dearth of antibiotic discovery in the pharmaceutical industry combine to create a critical need for new drug discovery. For the past several years, we have used a structure-based effort to develop a novel series of propargyl-linked antifolates that potently inhibit the essential enzyme dihydrofolate reductase (DHFR) and are effective against Gram-positive and eukaryotic pathogens. Additionally, these compounds show low rates of resistance and have good physicochemical properties. Recently, we have discovered that the propargyl-linked antifolates are potent inhibitors of K. pneumoniae in culture and against K. pneumoniae DHFR. Here, we propose to extend this class of antifolates to become excellent antibiotics against pathogenic Enterobacteriaceae. We propose three specific aims. In the first aim, we will develop inhibitors that are potent and selective inhibitors of K. pneumoniae and E. coli DHFR and potent inhibitors of wild-type and resistant Enterobacteriaceae, such as trimethoprim-, ESBL-, KPC- and NDM1-variants while maintaining low human cell toxicity. In the second aim, we will determine iterative crystal structures of wild- type and trimethoprim-resistant Enterobacteriaceae DHFRs as well as human DHFR, intended to drive the design of potent and selective compounds. The third aim will focus on studies in animals: an initial stage with a set of potent compounds begins with the evaluation of efficacy against wild-type strains and initial pharmacokinetic parameters. A second stage will evaluate efficacy against a range of phenotypes along with detailed pharmacokinetic/pharmacodynamic parameters. At the end of this proposal we expect to deliver a highly efficacious, orally available antifolate antibiotic against a broad range of Enterobacteriaceae isolates.