High-Throughput\nScreening of Antioxidant Drug Candidates\nfrom Natural Antioxidants with a “Zero” Intrinsic Fluorescence\nPeroxynitrite Sensing Precursor

The fluorescence high-throughput screening method is\nof importance\nfor new antioxidant drug candidate discovery for the treatment of\nserious hepatorenal syndrome, which displayed an obvious upregulated\nperoxynitrite level. However, most of the current ONOO<sup>–</sup> probes possessed incomplete fluorescence quenching efficiency, which\ncan result in non-negligible probe inherent fluorescence. Hence, we\nutilized the probe conjugated structure disruption strategy to construct\nhydrogenation phosphorus-substituted rhodamine (<b>H–PRh</b>) with “zero” probe inherent fluorescence character.\nBased on the precursor, a series of natural products were screened\nfor identifying antioxidant drug candidates. Luteolin was screened\nout by activating the Sirt1-Nrf2-HO-1 signaling pathway to regulate\nthe accumulation of ONOO<sup>–</sup> in the hepatorenal syndrome.\nOverall, the “zero” probe inherent fluorescence ONOO<sup>–</sup> sensor constructed here applies for a promising and\nversatile toolbox for illuminating the ONOO<sup>–</sup>-related\npathological process in the hepatorenal syndrome. Besides, this strategy\nof constructing highly sensitive sensors could serve as a valuable\nreference for further fluorescent probes.