ABSTRACTPeptide deformylase (PDF) is a prokaryotic metalloenzyme that is essential for bacterial growth and is a new target for the development of antibacterial agents. All previously reported PDF inhibitors with sufficient antibacterial activity share the structural feature of a 2-substituted alkanoyl at the P1′ site. Using a combination of iterative parallel synthesis and traditional medicinal chemistry, we have identified a new class of PDF inhibitors withN-alkyl urea at the P1′ site. Compounds with MICs of ≤4 μg/ml against gram-positive and gram-negative pathogens, includingStaphylococcusaureus,Streptococcuspneumoniae, andHaemophilusinfluenzae, have been identified. The concentrations needed to inhibit 50% of enzyme activity (IC50s) forEscherichiacoliNi-PDF were ≤0.1 μM, demonstrating the specificity of the inhibitors. In addition, these compounds were very selective for PDF, with IC50s of consistently >200 μM for matrilysin and other mammalian metalloproteases. Structure-activity relationship analysis identified preferred substitutions resulting in improved potency and decreased cytotoxity. One of the compounds (VRC4307) was cocrystallized with PDF, and the enzyme-inhibitor structure was determined at a resolution of 1.7 Å. This structural information indicated that the urea compounds adopt a binding position similar to that previously determined for succinate hydroxamates. Two compounds, VRC4232 and VRC4307, displayed in vivo efficacy in a mouse protection assay, with 50% protective doses of 30.8 and 17.9 mg/kg of body weight, respectively. TheseN-alkyl urea hydroxamic acids provide a starting point for identifying new PDF inhibitors that can serve as antimicrobial agents.
摘要肽变形酶(PDF)是一种原核生物金属酶,对细菌生长至关重要,是开发抗菌剂的新靶点。之前报道的所有具有足够抗菌活性的 PDF 抑制剂都有一个共同的结构特征,即在 P1′位点上有一个 2-取代的烷酰基。通过迭代平行合成和传统药物化学的结合,我们发现了一类新的 PDF 抑制剂,其 P1′位点上含有 N-烷基脲。我们发现了对革兰氏阳性和革兰氏阴性病原体(包括金黄色葡萄球菌、肺炎链球菌和流感嗜血杆菌)的 MIC ≤4 μg/ml 的化合物。抑制 EscherichiacoliNi-PDF 50%酶活性所需的浓度(IC50s)≤0.1 μM,这表明了抑制剂的特异性。此外,这些化合物对 PDF 具有很高的选择性,对母细胞蛋白酶和其他哺乳动物金属蛋白酶的 IC50 始终为 >200 μM。结构-活性关系分析确定了可提高效力和降低细胞毒性的优选替代物。其中一种化合物(VRC4307)与 PDF 进行了共晶体化,并确定了分辨率为 1.7 Å 的酶抑制剂结构。这一结构信息表明,脲化合物的结合位置与之前确定的琥珀酸羟肟酸酯的结合位置相似。在小鼠保护试验中,VRC4232 和 VRC4307 这两种化合物显示出体内疗效,50% 的保护剂量分别为 30.8 毫克/千克体重和 17.9 毫克/千克体重。这些 N-烷基脲羟肟酸为确定可用作抗菌剂的新型 PDF 抑制剂提供了一个起点。