Development of non-sedative, parasite-selective benzodiazepines to treat the neglected tropical disease schistosomiasis

摘要：被忽视的热带病血吸虫病是由感染血吸虫的寄生虫引起的。 &gt；全球有2.3亿人。目前的治疗方法只依赖于一种药物--吡喹酮(PZQ)。PZQ是 对新近获得的尚未达到性成熟的寄生虫无效。PZQ也不会杀人 直接感染血吸虫。这些缺点，以及出现抗药性寄生虫菌株的前景， 强调控制血吸虫病的替代疗法的必要性。长期目标是确定 改良的抗血吸虫药物。因此，这项提案将研究另一类化合物 具有公认的抗寄生虫活性的苯二氮卓类药物。苯二氮卓类药物导联对治疗 血吸虫病，但对导致镇静的人类GABA有很高的亲和力。总的目标是 这一应用是为了鉴定一种具有抗血吸虫活性的苯二氮卓的衍生物，甲氯硝西潘，它保留了抗血吸虫的 寄生活性和对引起镇静的GABAAR亚型缺乏亲和力。中心假设是 减少宿主GABAARs参与的苯二氮卓类药物治疗将最大限度地减少镇静和保留 血吸虫杀灭活动。这个项目的基本原理是，虽然宿主的镇静是由药物作用驱动的，但 α1GABAR，血吸虫基因组完全缺乏GABAAR。因此，GABAAR不能解释反 苯二氮类药物的寄生效应。相反，初步数据表明甲氯硝西仑对寄生虫起作用 钙离子通道。由于这种药物的“靶标上”寄生虫受体和“靶外”宿主受体是不同的，所以它 应该有可能开发具有更高选择性的治疗方法。这将通过追求两个具体的 目的：1)开发在哺乳动物α1GABAARs活性降低的甲氯硝西仑类似物。2)区块 甲硝西仑与α-1GABAAR拮抗剂混合液的体内镇静作用。在第一个目标下，我们将 甲氯硝西仑类似物的合成及其与其他亚型选择性苯二氮卓类药物的结合筛选 对哺乳动物伽巴尔的检测。GABAAR亲和力降低的化合物将被筛选出来 抗血吸虫以鉴定对寄生虫有选择性的衍生物。最后，将筛选出抗血吸虫配体 用小鼠血吸虫病模型来评估相对于甲硝西仑的疗效基准。在第二个 目的：我们将评估甲硝西潘(以及来自目标1的HITS)和阻断的体内镇静效果。 α1GABAR选择性拮抗剂的镇静作用。将使用旋转棒试验来确定镇静剂量 每种化合物，然后与不同比例的拮抗剂混合给药，以确定 一种能清除寄生虫的混合物，副作用最小。本文提出的研究具有重要意义。 因为它将推进新的血吸虫病先导--目前尚无治疗血吸虫病的药物获得FDA批准 从1982年开始。这项研究具有创新性，将陈博士在寄生虫学方面的专业知识与医学上的 库克博士的化学专业知识，他是GABAAR亚型的基本性质和药理学专家。

ABSTRACT: The neglected tropical disease schistosomiasis is caused by parasitic blood flukes that infect >230 million people worldwide. Current treatment is reliant on just one drug, praziquantel (PZQ). PZQ is ineffective against recently acquired parasites that have not reached sexual maturity. PZQ also does not kill schistosomes directly. These drawbacks, and the prospect of emerging treatment-resistant parasite strains, highlight the need for alternative therapies to control schistosomiasis. The long-term goal is to identify improved anti-schistosomal drugs. Therefore, this proposal will investigate an alternative group of compounds with proven anti-parasitic activity, benzodiazepines. Benzodiazepine leads are effective at treating schistosomiasis but have high affinity for the human GABAARs that cause sedation. The overall objective of this application is to identify derivatives of a schistocidal benzodiazepine, meclonazepam, that retain anti- parasitic activity and lack affinity for sedation-causing GABAAR sub-types. The central hypothesis is that that benzodiazepine therapies with decreased engagement of host GABAARs will minimize sedation and retain schistocidal activity. The rationale for this project is that while host sedation is driven by drug action at the α1GABAAR, schistosome genomes lack GABAARs entirely. Therefore, GABAARs cannot account for the anti- parasitic effects of benzodiazepines. Instead, preliminary data indicates that meclonazepam acts on parasite Ca2+ channels. Since the ‘on-target’ parasite receptor and ‘off-target’ host receptor for this drug are distinct, it should be possible to develop treatments with improved selectivity. This will be done by pursuing two specific aims: 1) Develop analogs of meclonazepam with decreased activity at mammalian α1GABAARs. 2) Block sedation in vivo by admixture of meclonazepam with α1GABAAR antagonists. Under the first aim, we will synthesize meclonazepam analogs and screen these and other sub-type selective benzodiazepines in binding assays against mammalian GABAARs. Compounds with decreased GABAAR affinity will then be screened against schistosomes to identify parasite-selective derivatives. Finally, schistocidal ligands will be screened in murine model of schistosomiasis to assess efficacy benchmarked relative to meclonazepam. In the second aim, we will assess the in vivo sedative effects of meclonazepam (as well as hits from Aim 1) and the blockade of sedation by α1GABAAR-selective antagonists. The rotarod test will be used to determine the sedating dose of each compound, which will then be administered in mixture with varying ratios of antagonists to determine an admixture that admixture clears parasites with minimized side effects. The research proposed is significant because it will advance new schistocidal leads – no drug to treat schistosomiasis has been FDA approved since 1982. This research is innovative, combining Dr. Chan’s expertise in parasitology with the medicinal chemistry expertise of Dr. Cook, an expert in fundamental properties and pharmacology of GABAAR subtypes.