A rapid-response red-emitting probe for peroxynitrite fluctuation and silymarin protection in drug-induced...

Drug-induced liver injury (DILI) is a clinically important condition caused by hepatotoxic drugs or their reactive metabolites, frequently linked to excessive reactive oxygen species (ROS) generation. Given the pivotal role of peroxynitrite (ONOO^-) in oxidative stress-mediated DILI progression, real-time tracking of its spatial-temporal dynamics is critical for mechanistic studies. We present a red-emitting fluorescent probe, LD-ONOO, engineered with a naphthylamide-based fluorophore and a phenylboronic acid pinacol ester as the ONOO^--specific trigger. This probe demonstrates ultrafast response kinetics (<30 s), a remarkably large Stokes shift (163 nm), and exceptional selectivity and sensitivity for ONOO^- over competing ROS. LD-ONOO enabled real-time monitoring of endogenous ONOO^- fluctuations in both cellular and zebrafish models. In vivo imaging in a DILI mouse model revealed pronounced ONOO^- upregulation, directly implicating its pathological role. Notably, silymarin treatment effectively normalized ONOO^- levels, demonstrating the therapeutic potential of this traditional Chinese medicine-derived compound in mitigating DILI. Our study not only delivers a versatile molecular imaging tool for investigating ONOO^--associated hepatotoxicity but also provides experimental validation for the application of natural compounds in DILI intervention strategies.