The unabated rise in bacterial resistance to conventional antibiotics, coupled with collateral damage to normal flora incurred by overuse of broad-spectrum antibiotics, necessitates the development of new antimicrobials targeted against pathogenic organisms. Here, we explore the antibacterial outcomes and mode of action of a prochelator that exploits the production of β-lactamase enzymes by drug-resistant bacteria to convert a nontoxic compound into a metal-binding antimicrobial agent directly within the microenvironment of pathogenic organisms. Compound PcephPT (phenylacetamido-cephem-pyrithione) contains a cephalosporin core linked to 2-mercaptopyridine N-oxide (pyrithione) via one of its metal-chelating atoms, which minimizes its preactivation interaction with metal ions and its cytotoxicity. Spectroscopic and chromatographic assays indicate that PcephPT releases pyrithione in the presence of β-lactamase-producing bacteria. The prochelator shows enhanced antibacterial activity against strains expressing β-lactamases, with bactericidal efficacy improved by the presence of low-micromolar copper in the growth medium. Metal analysis shows that cell-associated copper accumulation by the prochelator is significantly lower than that induced by pyrithione itself, suggesting that the location of pyrithione release influences biological outcomes. Low-micromolar (4–8 μg/mL) minimum inhibitory concentration (MIC) values of PcephPT in ceftriaxone-resistant bacteria compared with median lethal dose (LD₅₀) values greater than 250 μM in mammalian cells suggests favorable selectivity. Further investigation into the mechanisms of prochelators will provide insight for the design of new antibacterial agents that manipulate cellular metallobiology as a strategy against infection.

中文翻译：

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铜影响β-内酰胺酶激活的螯合剂对抗药性细菌的抗菌作用。

细菌对常规抗生素的抵抗力不断增强，再加上广谱抗生素的过度使用对正常菌群造成附带损害，因此有必要开发针对病原生物的新型抗菌剂。在这里，我们探讨了一种耐药性细菌产生β-内酰胺酶的酶的直接作用机理，该酶可在病原微生物的微环境内直接将无毒化合物转化为结合金属的抗微生物剂。化合物PcephPT（苯乙酰胺基-头孢-吡啶酮）含有连接2-巯基吡啶N的头孢菌素核心通过其金属螯合原子之一氧化-（吡啶酮），从而使其与金属离子的预活化相互作用和细胞毒性最小化。光谱和色谱分析表明，在产生β-内酰胺酶的细菌存在下，PcephPT释放巯氧吡啶。该螯合剂显示出对表达β-内酰胺酶的菌株增强的抗菌活性，并且通过在生长培养基中存在低微摩尔铜提高了杀菌效果。金属分析表明，长圆粒体与细胞相关的铜累积量显着低于巯氧吡啶酮本身所诱导的铜累积量，表明巯氧吡啶酮释放的位置会影响生物学结果。与头孢曲松抗性细菌相比，低头微摩尔浓度（4–8μg/ mL）的PcephPT最低抑菌浓度（MIC）值与中值致死剂量（LD₅₀）在哺乳动物细胞中的值大于250μM，表明具有良好的选择性。对螯合剂机制的进一步研究将为设计新的抗菌剂提供见解，这些抗菌剂可操纵细胞金属生物学作为抵抗感染的策略。