The lack of effective chemical tools capable of dynamic tracking of labile glyoxal species (GOS) [e.g., methylglyoxal (MGO) and glyoxal (GO)] levels with high selectivity over other relevant electrophilic species, particularly, formaldehyde (FA) and nitric oxide (NO), has significantly hampered the understanding of their roles in a complex metabolic network and disease progressions. Herein, we report the rational design of the bioinspired 4-(2-guanidino)-1,8-naphthalimide fluorescent probes NAP-DCP-1 and NAP-DCP-3 from arginine-specific protein modifications. These probes undergo facile reversible fluorophore-promoted deprotonation–cyclization of a guanidium ion with labile GOS to form exocyclic five-membered dihydroxyimidazolidines. The probe NAP-DCP-1 can differentiate GOS levels in the serum of diabetic mice and patients from nondiabetic ones, which correlate very well with glucose levels, providing the GOS level as a potential new biomarker for diabetes diagnosis. Notably, the endoplasmic reticulum (ER)-targeting probe NAP-DCP-3 enabled the study of GOS perturbation in ER under various stress conditions and led to the discovery that formaldehyde (FA), either exogenously added or endogenously generated, could induce GOS level increases in ER. This finding reveals the previous unknown connection of FA with upregulated GOS levels and suggests that GOS is a key metabolite in bridging one-carbon metabolism with glycolysis and the downstream cell redox status. Moreover, the probes also showed potentials in separate quantification of MGO and GO via ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) and unexpected selectivity modulation for GO over MGO via two-photon excitation. It is expected that probes reported herein provide powerful tools to study GOS level modulations in complex biological networks and would facilitate GOS-associated basic research and discovery.

中文翻译：

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荧光团促进灵活的去质子化和环外五元环的选择性和动态跟踪不稳定乙二醛的环化。

缺乏能够动态跟踪不稳定的乙二醛类（GOS）[例如，甲基乙二醛（MGO）和乙二醛（GO）]水平的有效化学工具，其对其他相关亲电物质，尤其是甲醛（FA）和一氧化氮（否）严重阻碍了对其在复杂的代谢网络和疾病进展中的作用的理解。在这里，我们报告精氨酸特异性蛋白质修饰的生物启发的4-（2-胍基）-1,8-萘二甲酰亚胺荧光探针NAP-DCP-1和NAP-DCP-3的合理设计。这些探针经过易变的荧光团促进的胍离子与不稳定的GOS的去质子化-环化反应，形成环外五元二羟基咪唑烷。探头NAP-DCP-1可以区分糖尿病小鼠和非糖尿病小鼠血清中的GOS水平，这与葡萄糖水平有很好的相关性，可将GOS水平作为糖尿病诊断的潜在新生物标志物。值得注意的是，内质网（ER）靶向探针NAP-DCP-3使得能够研究在各种压力条件下ER中的GOS扰动，并导致发现外源添加或内源性产生的甲醛（FA）可能导致ER中GOS含量增加。这一发现揭示了FA与GOS水平上调之间的未知联系，并表明GOS是桥接一碳代谢与糖酵解和下游细胞氧化还原状态的关键代谢产物。此外，这些探针还显示出通过超高效液相色谱-质谱法（UPLC-MS）分别定量MGO和GO的潜力，以及通过双光子激发对MGO上的GO进行意外的选择性调制的潜力。