Discovery of novel, orally bioavailable, antileishmanial compounds using phenotypic screening.
Discovery of novel, orally bioavailable, antileishmanial compounds using phenotypic screening.
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DOI：
10.1371/journal.pntd.0006157
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发表时间：
2017-12-01
影响因子：
3.8
通讯作者：
Landfear, Scott M
中科院分区：
文献类型：
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作者：
Ortiz, Diana;Guiguemde, W Armand;Landfear, Scott M
利什曼病是一种寄生虫感染，困扰着全世界约1200万人。批准的利什曼病药物治疗有几个限制，包括中度至重度毒性，耐药性增加和需要延长剂量。此外，米替福新是目前唯一的口服药物治疗这种感染。我们通过两步表型筛选来发现新的、有效的和口服生物可利用的抗利什曼病药物，从而解决了对新疗法的迫切需求。首先，我们使用核酸结合染料SYBR绿色I对大约60万个小分子进行了高通量筛选（HTS），以抑制寄生虫生命周期的前鞭毛体形式的生长。该筛选鉴定了约2，700种化合物，其在10 μ M的单点浓度下抑制生长超过65%。我们接下来使用这2700个化合物聚焦文库来鉴定对致病性巨噬细胞内无鞭毛体形式高度有效并且对宿主巨噬细胞表现出有限毒性的化合物。这种两步筛选策略在我们的收集中发现了九种独特的化学支架，包括两种先前描述的抗利什曼病药物。我们进一步分析了两种新型化合物的体外吸收、分布、代谢、排泄和体内药代动力学。这两种化合物经口服证明具有生物利用度，可使血浆暴露量高于半数最大有效浓度（EC50）浓度至少12小时。两种化合物在皮肤利什曼病小鼠模型中口服给药时均有效。两种化合物之一对锥虫（与利什曼原虫属相关的动质体寄生虫）具有强效活性。因此，这种化合物可以帮助控制多种寄生虫病。从我们的HTS命中中观察到的有希望的药代动力学特征和显著的体内功效突出了我们的两步表型筛选策略的实用性，并强烈表明这些新鉴定的支架的药物化学优化将导致口服抗寄生虫药物的有希望的候选物。
Leishmaniasis is a parasitic infection that afflicts approximately 12 million people worldwide. There are several limitations to the approved drug therapies for leishmaniasis, including moderate to severe toxicity, growing drug resistance, and the need for extended dosing. Moreover, miltefosine is currently the only orally available drug therapy for this infection. We addressed the pressing need for new therapies by pursuing a two-step phenotypic screen to discover novel, potent, and orally bioavailable antileishmanials. First, we conducted a high-throughput screen (HTS) of roughly 600,000 small molecules for growth inhibition against the promastigote form of the parasite life cycle using the nucleic acid binding dye SYBR Green I. This screen identified approximately 2,700 compounds that inhibited growth by over 65% at a single point concentration of 10 muM. We next used this 2700 compound focused library to identify compounds that were highly potent against the disease-causing intra-macrophage amastigote form and exhibited limited toxicity toward the host macrophages. This two-step screening strategy uncovered nine unique chemical scaffolds within our collection, including two previously described antileishmanials. We further profiled two of the novel compounds for in vitro absorption, distribution, metabolism, excretion, and in vivo pharmacokinetics. Both compounds proved orally bioavailable, affording plasma exposures above the half-maximal effective concentration (EC50) concentration for at least 12 hours. Both compounds were efficacious when administered orally in a murine model of cutaneous leishmaniasis. One of the two compounds exerted potent activity against trypanosomes, which are kinetoplastid parasites related to Leishmania species. Therefore, this compound could help control multiple parasitic diseases. The promising pharmacokinetic profile and significant in vivo efficacy observed from our HTS hits highlight the utility of our two-step phenotypic screening strategy and strongly suggest that medicinal chemistry optimization of these newly identified scaffolds will lead to promising candidates for an orally available anti-parasitic drug.