The highly rigid and planar scaffolds with π-conjugated systems have been widely considered to be indispensable for β-amyloid (Aβ) binding ligands. In this study, a library of diphenoxy compounds with different types of more flexible linkers as Aβ ligands were synthesized and evaluated. Most of them displayed good affinity (K_i < 100 nM) for Aβ_1–42 aggregates, and some ligands even showed values of K_i less than 10 nM. Structure–activity relationship analysis revealed that modification on the linkers or substituents tolerated great flexibility, which challenged the long-held belief that rigid and planar structures are exclusively favored for Aβ binding. Three ligands were labeled by iodine-125, and they exhibited good properties in vitro and in vivo, which further supported that this flexible scaffold was potential and promising for the development of Aβ imaging agents.

中文翻译：

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发现具有柔性接头的地苯氧基衍生物作为 β-淀粉样蛋白斑的配体。

具有 π 共轭系统的高度刚性和平面支架已被广泛认为是 β-淀粉样蛋白 (Aβ) 结合配体必不可少的。在这项研究中，合成并评估了具有不同类型的更灵活的接头作为 Aβ 配体的二苯氧基化合物库。它们中的大多数对 Aβ _1-42聚集体显示出良好的亲和力 ( K _i < 100 nM) ，一些配体甚至显示出K _i值小于 10nM。构效关系分析表明，接头或取代基的修饰具有很大的灵活性，这挑战了长期以来认为刚性和平面结构专用于 Aβ 结合的观点。三种配体被碘125标记，它们在体外和体内表现出良好的特性，进一步支持这种柔性支架在Aβ成像剂的开发中具有潜力和前景。