Development of bishydrazide-based fluorescent probes for the imaging of cellular peroxynitrite (ONOO^-) during...

Peroxynitrite (ONOO^-) is a critical ROS in living systems, and could induce lipid peroxidation which is the driver of ferroptotic cell death. Therefore, precise and rapid detection of cellular ONOO^- is critical for the deep study of the biological functions of ONOO^- during ferroptosis. Herein, we developed fluorescent probes (Rh-1, Rh-2 and Rh-3) for the rapid detection of intracellular ONOO^- during ferroptosis. These probes used bishydrazide groups as the reactive sites for ONOO^-. The response of these probes to ONOO^- resulted in the production of the emissive xanthene fluorophore, providing a marked enhancement in the fluorescence intensity at 561 nm. The probe Rh-3 exhibited prominent selectivity and sensitivity towards ONOO^-. Bioimaging experiments suggested that Rh-3 could be applied to image exogenous and endogenous ONOO^- in living cells. By fluorescence imaging, it was demonstrated that erastin-induced ferroptosis caused increased levels of the endogenous ONOO^-, and ferrostatin-1 (Fer-1) and vitamin E (VE) could markedly inhibit the excessive production of ONOO^- during ferroptosis in living cells.