Biochemistry Research Laboratory, Department of Chemistry , Sharif University of Technology , Tehran 111559516 , Iran.
Chem Res Toxicol. 2018 Oct 15;31(10):1092-1104. doi: 10.1021/acs.chemrestox.8b00210. Epub 2018 Sep 10.
Conformational diseases, constituting a large number of diseases, have been connected with protein misfolding, leading to aggregation known as amyloid fibrils. Mainly due to the lack of detailed molecular mechanisms, there has not been an effective drug to combat amyloid-associated diseases. Recently, a small organic pyridazine-based molecule (RS-0406) has shown significant reductions in amyloid fibrils in both in vitro and in vivo animal studies. However, no information on molecular details of inhibition for the small molecule has been reported. In this work, we have decided to explore structure-activity relationship of pyridazine-based compounds to investigate structural parameters for amyloid inhibition. A number of closely related derivatives of RS-0406 were designed and synthesized to delineate the roles of structural properties, including bulkiness and halogen bonding, hydrogen-bonding ability, and the position of substituents on the flanking aromatic rings of the synthetic molecules. To examine the effectiveness of the synthesized compounds, amyloid fibril formation of hen egg white lysozyme was measured in the presence of each synthetic molecule. Our results indicated that in addition to the type of the aryl substituent, their positions on the ring were also important for their inhibitory roles in amyloid fibrils formation. Moreover, a fluorinated compound turned out to be a more effective kinetic inhibitor, displaying a delayed fibril nucleation than the original lead compound. Furthermore, biochemical structural analyses and molecular dynamics simulation revealed that the pyridazine-based compounds may mediate the inhibition of amyloid fibrils through stabilization of the protein monomer during partially unfolded state. The cytotoxicity assay revealed that the amounts of amyloid intermediates were reduced in the presence of the synthetic compounds. Eventually, IC values were obtained for the synthetic compounds, and quantitative structure-activity relationship method was employed to suggest more effective amyloid inhibitors.
构象疾病构成了大量疾病，这些疾病与蛋白质错误折叠有关，导致聚集形成所谓的淀粉样纤维。主要由于缺乏详细的分子机制，目前还没有有效的药物来对抗与淀粉样蛋白相关的疾病。最近，一种基于小的有机哒嗪的分子（RS-0406）在体外和体内动物研究中均显示出对淀粉样纤维有明显的减少作用。然而，尚未有关于该小分子抑制的分子细节的信息报道。在这项工作中，我们决定探索基于哒嗪的化合物的构效关系，以研究抑制淀粉样蛋白的结构参数。设计并合成了许多与 RS-0406 密切相关的衍生物，以阐明结构性质的作用，包括体积和卤键、氢键能力以及合成分子侧翼芳环上取代基的位置。为了检验合成化合物的有效性，在每种合成分子存在的情况下测量了鸡卵清溶菌酶的淀粉样纤维形成情况。我们的结果表明，除了芳基取代基的类型外，它们在环上的位置对于它们在淀粉样纤维形成中的抑制作用也很重要。此外，氟化化合物被证明是一种更有效的动力学抑制剂，其纤维核形成延迟比原始先导化合物长。此外，生化结构分析和分子动力学模拟表明，基于哒嗪的化合物可能通过在部分展开状态下稳定蛋白质单体来介导对淀粉样纤维的抑制。细胞毒性测定表明，在合成化合物存在的情况下，淀粉样中间产物的量减少。最终，获得了合成化合物的 IC 值，并采用定量构效关系方法提出了更有效的淀粉样蛋白抑制剂。
