Du Yimeng, Zhang Yuqing, Huang Meirong, Wang Shushu, Wang Jianzheng, Liao Kongke, Wu Xiaojun, Zhou Qiang, Zhang Xinhao, Wu Yun-Dong, Peng Tao
State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School Shenzhen 518055 China
Shenzhen Bay Laboratory Shenzhen 518132 China
Chem Sci. 2021 Oct 5;12(41):13857-13869. doi: 10.1039/d1sc04387k. eCollection 2021 Oct 27.
Increasing evidence has highlighted the endogenous production of formaldehyde (FA) in a variety of fundamental biological processes and its involvement in many disease conditions ranging from cancer to neurodegeneration. To examine the physiological and pathological relevance and functions of FA, fluorescent probes for FA imaging in live biological samples are of great significance. Herein we report a systematic investigation of 2-aza-Cope reactions between homoallylamines and FA for identification of a highly efficient 2-aza-Cope reaction moiety and development of fluorescent probes for imaging FA in living systems. By screening a set of -substituted homoallylamines and comparing them to previously reported homoallylamine structures for reaction with FA, we found that -methoxybenzyl homoallylamine exhibited an optimal 2-aza-Cope reactivity to FA. Theoretical calculations were then performed to demonstrate that the -substituent on homoallylamine greatly affects the condensation with FA, which is more likely the rate-determining step. Moreover, the newly identified optimal -methoxybenzyl homoallylamine moiety with a self-immolative β-elimination linker was generally utilized to construct a series of fluorescent probes with varying excitation/emission wavelengths for sensitive and selective detection of FA in aqueous solutions and live cells. Among these probes, the near-infrared probe FFP706 has been well demonstrated to enable direct fluorescence visualization of steady-state endogenous FA in live mouse brain tissues and elevated FA levels in a mouse model of breast cancer. This study provides the optimal aza-Cope reaction moiety for FA probe development and new chemical tools for fluorescence imaging and biological investigation of FA in living systems.
越来越多的证据表明，甲醛（FA）在多种基本生物过程中内源性产生，并且参与从癌症到神经退行性变等多种疾病状态。为了研究FA的生理和病理相关性及功能，用于在活生物样品中对FA进行成像的荧光探针具有重要意义。在此，我们报告了对高烯丙基胺与FA之间的2-氮杂-Cope反应进行的系统研究，以鉴定高效的2-氮杂-Cope反应部分，并开发用于在活体系统中对FA进行成像的荧光探针。通过筛选一组取代的高烯丙基胺，并将它们与先前报道的与FA反应的高烯丙基胺结构进行比较，我们发现甲氧基苄基高烯丙基胺对FA表现出最佳的2-氮杂-Cope反应活性。然后进行理论计算以证明高烯丙基胺上的取代基极大地影响与FA的缩合，这更可能是速率决定步骤。此外，新鉴定的具有自牺牲β-消除连接基的最佳甲氧基苄基高烯丙基胺部分通常用于构建一系列具有不同激发/发射波长的荧光探针，用于在水溶液和活细胞中灵敏且选择性地检测FA。在这些探针中，近红外探针FFP706已被充分证明能够直接荧光可视化活小鼠脑组织中的稳态内源性FA以及乳腺癌小鼠模型中升高的FA水平。这项研究为FA探针开发提供了最佳的氮杂-Cope反应部分，并为活体系统中FA的荧光成像和生物学研究提供了新的化学工具。
