Nutrient-Mediated Delivery of Antimicrobials

营养素介导的抗菌药物输送

• 批准号: 1937600
• 金额: --
• 依托单位: University of York
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-1937600
• 关键词: Nutrient; Mediated; Delivery; Antimicrobials

BackgroundThe problem of antimicrobial resistance is now so severe that it has been described as critical by the World Health Organisation and some authorities believe that mankind is now entering a post-antibiotic era. Fluoroquinolones (FQ) such as ciprofloxacin are widely used for the treatment of a range of infections, however, with their increased use the incidence of resistance in almost all bacteria that fluoroquinolones are used against has emerged.The challenge is to chemically modify FQs to increase intracellular concentrations and overcome permeability and efflux mediated resistance.We have explored the use of bacterial nutrient transport to deliver antibiotics into the bacterial cell (Trojan horse approach). To date we have investigated iron carriers (siderophores-citrate, Staphyloferrin A) and carbohydrates attached to the piperazinyl nitrogen of ciprofloxacin via a non-biolabile linker. Screens against our established panel of bacterial strains confirmed that ciprofloxacin, when conjugated, retains antibacterial activity, however, its potency is reduced. Subsequent DNA gyrase inhibition assays revealed that the decrease in activity is mainly due to an impaired ability of the ciprofloxacin conjugate to inhibit gyrase, the target of the drug, rather than lack of bacterial uptake. We believe that the presence of the conjugated moiety limit binding to DNA gyrase5-7. This suggests that a 'prodrug approach', were the nutrient is cleaved, with intracellular release of the fluoroquinolone will improve Project Aims: The primary aim of this research is to conjugate FQs to key nutrients via an intracellular, reductively activated, biolabile linker in order to evade FQ permeability resistance and increase intracellular accumulation. The research workflow is: (1) To synthesise a ciprofloxacin conjugates with a self immolative linker. The design of the linker is such that, after active transport, intracellular reduction (via intracellular sulfhydryl-containing species such as glutathione) will release free ciprofloxacin in the bacterial cytoplasm. Initially the conjugate will use a citrate unit (our model siderophore) attached to FQ COOH. The conjugate will be screened against wild-type E. coli. The minimum inhibitory concentrations/minimum bactericidal concentrations obtained will be compared to those of the parent drug ciprofloxacin and a corresponding analog with non-labile linker. (2) The siderophore components that we propose to explore are inspired by the structure of the salmochelins, a new class of siderophores that has only recently discovered. The main advantage of these glycosylated siderophores is that they are able to evade the immune response of the mammalian host. In addition, they are less susceptible to serum albumin binding and membrane partitioning, both factors that reduce the concentration of conventional siderophores in the serum.

背景抗菌素耐药性的问题现在是如此严重，它已被世界卫生组织描述为关键，一些权威人士认为，人类现在正在进入一个后抗生素时代。氟喹诺酮（FQ）如环丙沙星广泛用于治疗一系列感染，然而，随着其使用的增加，几乎所有使用氟喹诺酮类药物的细菌都出现了耐药性。挑战在于化学修饰FQs以增加细胞内浓度并克服渗透性和外排介导的耐药性。我们探索了使用细菌营养转运将抗生素递送到细菌细胞（特洛伊木马方法）。到目前为止，我们已经研究了铁载体（铁载体柠檬酸盐，葡萄铁蛋白A）和碳水化合物连接到哌嗪氮环丙沙星通过非生物不稳定的接头。针对我们建立的细菌菌株组的筛选证实，环丙沙星在缀合时保留抗菌活性，然而，其效力降低。随后的DNA促旋酶抑制测定揭示，活性的降低主要是由于环丙沙星缀合物抑制促旋酶（药物的靶标）的能力受损，而不是缺乏细菌摄取。我们认为，结合部分的存在限制了与DNA促旋酶的结合5 -7。这表明，“前药方法”，其中营养素被切割，氟喹诺酮的细胞内释放将改善项目目标：本研究的主要目的是通过细胞内还原活化的生物不稳定接头将FQ与关键营养素缀合，以逃避FQ渗透性抗性并增加细胞内积累。研究工作流程为：（1）合成具有自分解连接基的环丙沙星偶联物。接头的设计使得在主动转运后，细胞内还原（通过细胞内含巯基物质如谷胱甘肽）将在细菌细胞质中释放游离的环丙沙星。最初，结合物将使用连接到FQ COOH的柠檬酸盐单元（我们的模型铁载体）。将针对野生型E.杆菌将获得的最小抑菌浓度/最小杀菌浓度与母体药物环丙沙星和具有非不稳定接头的相应类似物的最小抑菌浓度/最小杀菌浓度进行比较。(2)我们提出探索的铁载体成分的灵感来自于salmochelins的结构，这是一种新的铁载体，最近才发现。这些糖基化铁载体的主要优点是它们能够逃避哺乳动物宿主的免疫应答。此外，它们对血清白蛋白结合和膜分配不太敏感，这两个因素都会降低血清中常规铁载体的浓度。