Methionyl-tRNA Synthetase inhibitors can be developed as novel Giardiasis therapeutics

项目摘要/摘要 蓝氏贾第鞭毛虫是引起贾第虫病的病原体，贾第虫病是一种胃肠道疾病，症状包括腹泻。 和吸收不良。慢性感染会导致婴儿长期发育迟缓或死亡，最近的一种 据估计，全球每年有2.8亿个有症状病例。然而，相当数量的临床 感染对目前可用的治疗方法，特别是甲硝唑具有抗药性。我们已经展示了具体的 甲硫酰-tRNA合成酶(MetRS)的抑制剂在可用的~600库中代表3个支架，可防止 野生型和甲硝唑抗性蓝氏菌菌株的生长。分子作用机制似乎 这可能是由于GlMetRs酶的活性被抑制而导致蓝藻蛋白质合成的中断。证明 主要化合物1717具有良好的口服生物利用度，是一种有效的治疗小鼠模型 贾第虫病，3天后蓝氏贾第鞭毛虫完全清除。这项研究计划将利用这些 鼓励初步数据开发化合物作为替代或补充的新型抗贾第虫药物 贾第鞭毛虫病的治疗。我们选择了18种化合物，代表了3种不同的基于化学的支架 官能团多样性，GlMetRS IC50≤50 nm，革兰氏菌滋养体EC50≤3000 nm，以及选择性指数 ≥15定义为CC50/EC50，用于肝癌细胞培养的毒性。初步数据显示，双环 与其他两个系列相比，连接剂系列往往具有更好的选择性。因此，我们将重点关注 双环连接物。有效抗贾第鞭毛虫的药代动力学相关性 化疗还没有很好的建立，我们将使用这些化合物来定义PK/PD的性质 在目标1中，我们将确定结构活性关系 筛选出对GlMetRS和多株革兰氏菌具有高效抗菌活性的化合物。在目标2中，我们将 确定：静态属性与杀伤性、杀伤率、获得性抗性倾向和初始安全责任 这些化合物中。基于结构的设计、经验合成孔径雷达驱动方法和自动化的组合 目标3将利用蓝氏贾第鞭毛虫的定量断层扫描来指导双黄连的药物化学优化。 环形链接器脚手架，用于提高疗效和PK/ADMET性能，同时解决潜在的安全问题。 我们将在体外和啮齿动物模型中确定GlMetRS抑制剂的潜在毒性和非靶点效应。这个 将测试化合物的HERG易感性和CYP抑制，以及针对突变模型和 一个由人体受体和离子通道组成的安全面板。这将为目标4中的剂量发现实验奠定基础。 在疗效模型、最终毒理学研究、额外耐药性研究和甲硝唑联合研究中。 拟议的工作将完成选择临床前候选人的许多必要步骤，这将 促进革兰氏菌相关性慢性无症状疾病、腹泻、 发育迟缓，认知功能差。该产品将对公众健康有很大的好处。

Project Summary/Abstract Giardia lamblia is the causative agent of giardiasis, a gastrointestinal illness with symptoms including diarrhea and malabsorption. Chronic infections can lead to long term growth retardation or death in infants, with a recent estimate of global incidence of 280 million symptomatic cases per year. However, a substantial number of clinical infections are resistant to currently available treatments, especially metronidazole. We have shown that specific inhibitors of methionyl-tRNA synthetase (MetRS) representing 3 scaffolds in an available ~600 library prevent growth in wild-type and metronidazole resistant G. lamblia strains. The molecular mechanism of action seems to be the disruption of G. lamblia protein synthesis due to inhibition of GlMetRS enzyme activities. Proof of principle compound 1717 has decent oral bioavailability and is an effective treatment in a mouse model of giardiasis, showing complete clearance of G. lamblia after 3 days. This research proposal will capitalize on these encouraging preliminary data to develop compounds as novel anti-giardia drugs for alternative or complementary treatment of giardiasis. We have selected 18 compounds representing 3 distinct scaffolds based on chemical functional group diversity, GlMetRS IC50 ≤50nM, G. lamblia trophozoite EC50 ≤3000nM, and a selectivity index of ≥ 15 defined as CC50/EC50, for toxicity in HepG2 cell cultures. Preliminary data showed that the double-ring linker series tends to have better selectivity when compared to the other two series. We will therefore focus on the double-ring linker compounds. Since the pharmacokinetic correlations for effective anti-Giardia chemotherapy have not been well established, we will use these compounds to define the PK/PD properties necessary for optimum in vivo efficacy in Aim 1. Also, in Aim 1, we will determine structural activity relationships and select compounds with high potency against GlMetRS and multiple G. lamblia strains. In Aim 2, we will determine: static vs. cidal properties, rate of killing, propensity for acquired resistance and initial safety liabilities of the compounds. A combination of structure-based design, empirical SAR-driven approaches and automated quantitative tomography of G. lamblia will be used in Aim 3 to guide medicinal chemistry optimization of double- ring linker scaffold for improved efficacy and PK/ADMET properties, while addressing potential safety issues. We will determine potential toxicity and off-target effects of GlMetRS inhibitors in vitro and in rodent models. The compounds will be tested for hERG liabilities and CYP inhibition, as well as against the mutagenesis model and a safety panel of human receptors and ion channels. This will set the stage in Aim 4 for dose finding experiments in efficacy models, final toxicology studies, additional resistance studies and metronidazole combination studies. The proposed work will complete many of the steps necessary for selecting a preclinical candidate that will facilitate innovative, shorter course therapy for G. lamblia-associated chronic asymptomatic diseases, diarrhea, growth retardation, and poor cognitive function. The product will provide a great public health benefit.