Amyloid fibrils formed by a variety of peptides are biological markers of different human diseases, such as Alzheimer’s disease, Parkinson’s disease, and type II diabetes, and are structural constituents of bacterial biofilms. Novel fluorescent probes offering improved sensitivity or specificity toward that diversity of amyloid fibrils or providing alternative spectral windows are needed to improve the detection or the identification of amyloid structures. One potential source for such new probes is offered by molecules known to interact with fibrils, such as the inhibitors of amyloid aggregation found in drug discovery projects. Here we show the feasibility of the approach by designing, synthesizing, and testing several pyrene-based fluorescent derivatives of a previously discovered inhibitor of the aggregation of the Aβ_1–42 peptide. All the derivatives tested retain the interaction with the amyloid architecture and allow its staining. The most soluble derivative, N-acetyl-2-(2-methyl-4-oxo-5,6,7,8-tetrahydro-4H-benzo[4,5]thieno[2,3-d][1,3]oxazin-7-yl)-N-(pyren-1-ylmethyl)acetamide (compound 1D), stains similarly well amyloid fibrils formed by Aβ_1–42, α-synuclein, or amylin, provides a sensitivity only slightly lower than that of thioflavin T, displays a large Stokes shift, allows efficient excitation in the UV spectral region, and is not cytotoxic. Compound 1D can also stain amyloid fibrils formed by staphylococcal peptides present in biofilm matrices and can be used to distinguish, by direct staining, Staphylococcus aureus biofilms containing amyloid-forming phenol-soluble modulins from those lacking them.

中文翻译：

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具有大斯托克斯位移的pyr抑制剂荧光探针，用于染色Aβ1–42，α-突触核蛋白和淀粉样蛋白淀粉样蛋白原纤维以及含淀粉样蛋白的金黄色葡萄球菌生物膜

由多种肽形成的淀粉样蛋白原纤维是不同人类疾病（例如阿尔茨海默氏病，帕金森氏病和II型糖尿病）的生物学标记，并且是细菌生物膜的结构成分。为了改善淀粉样蛋白结构的检测或鉴定，需要新颖的荧光探针，其对淀粉样蛋白原纤维的多样性提供改进的灵敏度或特异性，或者提供替代的光谱窗口。这种新探针的潜在来源是已知与原纤维相互作用的分子，例如在药物开发项目中发现的淀粉样蛋白聚集抑制剂。在这里，我们通过设计，合成和测试先前发现的Aβ聚集抑制剂的几种pyr基荧光衍生物来显示该方法的可行性_1–42肽。所有测试的衍生物都保留了与淀粉样结构的相互作用，并允许其染色。最易溶的衍生物N-乙酰基-2-（2-甲基-4-氧代-5,6,7,8-四氢-4 H-苯并[4,5]噻吩并[2,3- d ] [1， 3] oxazin-7-yl）-N-（pyren-1-ylmethyl）acetamide（化合物1D），对由_Aβ1–42，α-突触核蛋白或胰岛淀粉样多肽形成的淀粉样原纤维染色同样好，其敏感性仅略低于硫黄素T具有明显的斯托克斯位移，可在紫外光谱区域内有效激发，且无细胞毒性。化合物1D还可以染色生物膜基质中存在的葡萄球菌肽形成的淀粉样原纤维，并且可以通过直接染色来区分，金黄色葡萄球菌生物膜含有淀粉样蛋白形成的酚溶性调节蛋白，而缺乏生物膜。