Propargyl-linked Antifolates Targeting Klebsiella pneumoniae

描述（由申请方提供）：由于对几类抗生素（包括青霉素类、头孢菌素类、碳青霉烯类、氟喹诺酮类和抗叶酸剂）的广泛耐药性，肠杆菌科（主要是革兰氏阴性病原体肺炎克雷伯菌和大肠埃希菌）引起的感染越来越难以治疗。沿着耐药性，天然有限的一系列有效对抗革兰氏阴性病原体的药剂和制药工业中抗生素发现的缺乏结合联合收割机产生了对新药发现的迫切需要。在过去的几年里，我们已经使用了基于结构的努力，开发了一系列新的炔丙基连接的抗叶酸剂，有效地抑制必需酶二氢叶酸还原酶（DHFR），并有效地对抗革兰氏阳性和真核病原体。此外，这些化合物显示出低抗性率并具有良好的物理化学性质。最近，我们发现炔丙基连接的抗叶酸剂是K. pneumoniae对K.肺炎DHFR。在这里，我们建议将这类抗叶酸剂扩展为针对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，我们将开发抑制剂，是有效的和选择性的抑制剂K。pneumoniae和E.大肠杆菌DHFR和野生型和耐药肠杆菌科的有效抑制剂，如甲氧苄啶-、ESBL-、KPC-和NDM 1-变体，同时保持低的人类细胞毒性。在第二个目标中，我们将确定野生型和甲氧苄啶耐药肠杆菌科DHFR以及人类DHFR的迭代晶体结构，旨在推动有效和选择性化合物的设计。第三个目标将集中在动物研究：一组有效化合物的初始阶段开始于对野生型菌株的功效和初始药代动力学参数的评估。第二阶段将评价针对一系列表型的疗效沿着详细的药代动力学/药效学参数。在本提案的最后，我们期望提供一种高效的、口服的抗叶酸抗生素，以对抗广泛的肠杆菌科分离株。

DESCRIPTION (provided by applicant): 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.