AbstractLatent cyclic carbon‐centered nucleophiles (latent C‐nucleophiles) are recently proving their value in the field of reaction‐based fluorescent probes, far beyond their primary utility in organic synthesis. They are typically used to introduce a Michael acceptor moiety acting as a recognition/reaction site for analyte to be detected or as a kinetic promoter of fluorogenic cascade reactions triggered by a reactive species. C‐nucleophiles bearing a further reactive handle offer an additional opportunity for tuning the physicochemical/targeting properties or providing drug‐releasing capabilities to these probes, through the covalent attachment of ad hoc chemical moiety. In order to implement such strategy to fluorogenic/chromogenic enzyme substrates based on the “covalent‐assembly” principle, we have explored the potential of some functionalized derivatives of barbituric acid, piperidine‐2,4‐dione and Meldrum's acid. Our investigations based on the rational design and analytical validations of enzyme‐responsive caged precursors of fluorescent pyronin dyes and 7‐(diethylamino)coumarin‐3‐carboxylic acid, led to identify a versatile candidate suitable for this late‐stage structural optimization approach. This Meldrum's acid derivative enables to either enhance water solubility or achieve the reversible conjugation of a targeting ligand, while promoting in situ formation of fluorophore upon enzymatic activation. This study opens the way to novel multifunctional fluorescence imaging probes and optically modulated small conjugate‐based theranostics.
摘要潜伏环碳中心亲核物(潜伏 C-亲核物)最近证明了它们在基于反应的荧光探针领域的价值,远远超出了它们在有机合成中的主要用途。它们通常用于引入迈克尔受体分子,作为待检测分析物的识别/反应位点,或作为反应物引发的荧光级联反应的动力学促进剂。带有进一步反应柄的 C-亲核物为调整探针的理化/靶向特性提供了额外的机会,或通过共价连接特设化学分子为这些探针提供药物释放功能。为了在 "共价组装 "原理的基础上将这种策略应用于氟原酶/色原酶底物,我们探索了巴比妥酸、哌啶-2,4-二酮和梅尔德鲁姆酸的一些官能化衍生物的潜力。我们的研究基于对荧光吡罗宁染料和 7-(二乙基氨基)香豆素-3-羧酸的酶反应性笼式前体的合理设计和分析验证,最终确定了一种适合这种后期结构优化方法的多功能候选物质。这种梅尔德伦酸衍生物既能提高水溶性,又能实现与靶向配体的可逆共轭,同时还能在酶激活时促进荧光团的原位形成。这项研究为新型多功能荧光成像探针和基于光学调制小共轭物的治疗技术开辟了道路。