A fluorescent probe for concurrent detection of cysteine, homocysteine, and superoxide anion

Redox imbalance is a key factor in the pathogenesis of diseases such as epilepsy and liver injury. Superoxide anion (O₂^•-), cysteine (Cys), and homocysteine (Hcy) play central roles in maintaining redox homeostasis, and their dysregulation drives oxidative stress and disease progression. Here, we report a multifunctional fluorescent probe, BPC, capable of simultaneously and selectively detecting Cys, Hcy, and O₂^•- in complex biological environments. BPC shows high sensitivity, selectivity, and biocompatibility, enabling real-time visualization of redox fluctuations in living cells and zebrafish with minimal cytotoxicity. In pentylenetetrazole (PTZ)- and acetaminophen (APAP)-induced models of epilepsy and liver injury, BPC revealed notable alterations in Cys, Hcy, and O₂^•- levels, providing mechanistic insights into redox dysregulation. Moreover, BPC successfully tracked redox restoration following <i>N</i>-acetylcysteine (NAC) treatment. These findings establish BPC as a versatile tool for redox biology and highlight its promise for diagnostic and therapeutic applications.