ll together with the areas of CYP2E1 expression and GSH depletion (Fig. 5f). Taken together, the constructed HRMS/MS library of oxPCs and in vivo 18O labeling permitted us to HSPA5 Synonyms visualize oxPCs selectively using a restricted background noise and provided important data around the oxPC formation web site within the tissues of animal illness models. Discussion Herein, we clarified the structures of 155 oxPCs (103 novel oxPCs) derived from three PUFA-PCs applying an LC/HRMS/MSbased nontargeted method. Until now, several researchers have explored novel oxGPLs according to the structures of well-known lipid mediators as well as the proposed LPO mechanisms34,35. Nevertheless, as the precise LPO mechanism remains unclear, the prediction of all individual LPO merchandise is challenging. In fact, the structures of some newly identified oxPCs, like PC16:0_8:0 and PC16:0_17:3;O2, could have hardly been predicted from the previously reported mechanisms16,368. Nevertheless, the abovementioned compounds have been identified in our animal disease model (Fig. 3d). These benefits indicate that a nontargeted method is needed for the exhaustive identification of diverse oxPCs. Furthermore, structural facts around the newly identified oxPCs is expected to facilitate the elucidation of novel LPO mechanisms. The item profiles of oxPCs depended around the presence or absence of metal ions (Fig. 2a). In metal-free LPO systems, including those employing AAPH stimulation or autoxidation, hydrogen atom abstraction by radical initiators resulted in an excessive accumulation of lipid hydroperoxides, as reported previously8. In contrast, metal ions enhanced the decomposition of lipid hydroperoxides to a wide selection of secondary oxidation solutions, including lipid ketones, hydroxides, epoxides, and epoxy-hydroxides (Supplementary Fig. 14), as reported previously16,19. As described above, the LPO product profiles depended on reaction circumstances, and our developed library covered the structures of different oxPCs, regardless of their individual generation mechanisms, enabling the productive detection of 70 endogenous oxPCs formed in the course of APAPinduced ALF (Fig. 4). The exhaustive evaluation also revealed the exclusive Caspase 4 site kinetic profiles of endogenous oxPCs. In particular, the levels of Pc PUFA;O2 predominantly enhanced in the early phase of liver injury (Fig. four), and also the accumulation regions matched the locations of CYP2E1 expression and GSH depletion (Fig. five), indicating the value of oxPCs in ALF progression. The detected species contained epoxide and hydroxide moieties possibly formed by means of metal ion-induced peroxidation (Figs. 2d and 4c ). In addition, our detailed structural analysis of PC16:0_18:2;18O2 generated in mice that had inhaled 18O2, and have been treated for 2 h with APAP validated the estimated structures (Supplementary Fig. 15). Prior research showed that pretreatment with an iron chelator, viz. deferoxamine, inhibits the hepatotoxicity caused by APAP26. In addition, APAP overdose causes the translocation of iron from lysosomes to mitochondria, inducing mitochondrial oxidative stressNATURE COMMUNICATIONS | (2021)12:6339 | doi.org/10.1038/s41467-021-26633-w | nature/naturecommunicationsNATURE COMMUNICATIONS | doi.org/10.1038/s41467-021-26633-wARTICLEc184.aAPAP injection (300 mg/kg)b100MS intensity ( ) PC34:two;18O2 m/z 794.IntensityPC34:two;18O774.5538 (-H218O)794.(precursor ion)50 0 20018O air050 0PC36:four;18O2 m/z 818.Intensity100 50184.PC36:four;18O798.5537 (-H218O)818.(precursor ion)18Olabeling (120 min)50PC38:six;18O2 m/z 842.I