Target identification and structure optimization of novel thiazole antifungals

描述(由申请人提供)：目前系统性真菌感染的治疗选择仍然有限。真菌和宿主细胞之间的结构和代谢相似，以及由此产生的宿主毒性的可能性，使新抗真菌药物的开发变得复杂。常用的针对真菌细胞膜甾醇的多烯和三氮唑类抗真菌药，也会影响哺乳动物细胞膜胆固醇的稳定性和产生。新近开发的棘球菌素对真菌靶标更具特异性，但它们对组织胞浆菌和新生隐球菌的治疗无效，使宿主毒性多烯和三氮唑成为治疗这些病原体引起的感染的唯一方法。从结构上与嘌呤相似的小分子文库(如ATP/GTP、NADP等)中，我们鉴定了一系列基于噻唑的化合物，它们对组织胞浆菌和新生隐球菌有很强的抗真菌活性。重要的是，这些化合物不仅抑制培养中的真菌细胞，而且还抑制感染后驻留在哺乳动物宿主细胞内的真菌细胞。用噻唑类抗真菌药物治疗感染组织胞浆的巨噬细胞可保护宿主细胞免受组织胞浆诱导的细胞死亡。为了使最受欢迎的抗真菌药物噻唑成熟成为药物开发的首选候选药物，并更好地了解其作用机制，本研究方案试图利用亲和力和化学蛋白质组学确定抗真菌噻唑的细胞靶点(S)，并使用动物模型进行初步的体内疗效和毒性研究。此外，将制备和测试噻唑的衍生物，以确定抗真菌活性所需的结构特征和 以改善其化学性质，最大限度地发挥抗真菌效力。

DESCRIPTION (provided by applicant): Current treatment options for systemic fungal infections remain limited. The development of new antifungals is complicated by the structural and metabolic similarities among fungal and host cells, and the consequent potential for host toxicity. The commonly used polyene and triazole antifungals, which target fungal cell membrane sterols, also affect the stability and production of mammalian cell membrane cholesterol. The recently developed echinocandins are more specific for fungal targets, however they are ineffective in the treatment of Histoplasma capsulatum and Cryptococcus neoformans, leaving the host-toxic polyenes and triazoles as the only methods for treatment of infections caused by these pathogens. From a library of small molecules with structural similarities to purines (e.g., ATP/GTP, NADP, etc.), we identified a series of thiazole-based compounds that have potent antifungal activity against Histoplasma capsulatum and Cryptococcus neoformans. Importantly, these compounds inhibit not only fungal cells in culture but also fungal cells that reside within mammalian host cells following infection. Treatment of Histoplasma-infected macrophages with the thiazole-based antifungals protects host cells from Histoplasma- induced cell death. To mature the top hit antifungal thiazole into a lead candidate for drug development and to better understand its mode of action, this research proposal seeks to identify the cellular target(s) of the antifungal thiazole using affinity and chemical proteomics and to provide initial n vivo efficacy and toxicity studies using an animal model. In addition, derivatives of the thiazole will be prepared and tested to define the structural features necessary for antifungal activity and to improve its chemical properties and maximize antifungal potency.