College of Pharmacy and Research Institute of Life and Pharmaceutical Sciences, Sunchon National University, Suncheon 57922, Korea.
College of Pharmacy, Pusan National University, Busan 46241, Korea.
Molecules. 2019 Sep 3;24(17):3206. doi: 10.3390/molecules24173206.
Xanthene fluorophores, including fluorescein, rhodol, and rhodamines, are representative classes of fluorescent probes that have been applied in the detection and visualization of biomolecules. "Turn on" activatable fluorescent probes, that can be turned on in response to enzymatic reactions, have been developed and prepared to reduce the high background signal of "always-on" fluorescent probes. However, the development of activity-based fluorescent probes for biological applications, using simple xanthene dyes, is hampered by their inefficient synthetic methods and the difficulty of chemical modifications. We have, thus, developed a highly efficient, versatile synthetic route to developing chemically more stable reduced xanthene fluorophores, based on fluorescein, rhodol, and rhodamine via continuous Pd-catalyzed cross-coupling. Their fluorescent nature was evaluated by monitoring fluorescence with variation in the concentration, pH, and solvent. As an application to activatable fluorescent probe, nitroreductase (NTR)-responsive fluorescent probes were also developed using the reduced xanthene fluorophores, and their fluorogenic properties were evaluated.
香豆素类荧光团，包括荧光素、若丹明和罗丹明，是荧光探针的代表性类别，已被应用于生物分子的检测和可视化。“开启型”可激活荧光探针可响应酶反应而被激活，以降低“常开型”荧光探针的高背景信号。然而，使用简单的香豆素染料开发基于活性的荧光探针用于生物应用受到其低效合成方法和化学修饰困难的阻碍。因此，我们开发了一种高效、通用的合成方法，通过连续 Pd 催化交叉偶联，以荧光素、若丹明和罗丹明为基础，开发出化学稳定性更高的还原香豆素荧光团。通过监测浓度、pH 值和溶剂变化时的荧光来评估其荧光性质。作为可激活荧光探针的应用，还使用还原香豆素荧光团开发了硝基还原酶（NTR）响应的荧光探针，并对其荧光性质进行了评估。
