Integrated Proteomics, Biological Functional Assessments, and Metabolomics Reveal Toosendanin-Induced Hepatic Energy Metabolic Disorders.

Toosendanin (TSN), a compound from Melia toosendan, exhibits severe hepatotoxicity, which restricts its clinical application. However, the mechanism is not clear. Our previous research found that covalent modification of TSN for proteins might be a possible reason using human liver microsomes, and the glycolytic enzymes, triosephosphate isomerase 1 (TPIS) and α-enolase (ENOA), were responsible for the hepatotoxicity. In this study, we tried to prove these findings in cell and animal models by integration of proteomics, metabolomics, and biological methods. Proteomics analysis in rats showed that TPIS and ENOA were covalently modified by TSN reactive metabolites. The biological functional assessments revealed that the modifications inhibited the activity of TPIS and induced the activity of ENOA, in vitro and in vivo, followed by an increase in the level of cellular methylglyoxal, advanced glycation end products, and reactive oxygen species/superoxide, and the induction of mitochondrial dysfunction, which further inhibited oxidative phosphorylation and stimulated glycolysis. Furthermore, metabolomics demonstrated the decrease in the level of metabolites in the tricarboxylic acid cycle, fatty acid β-oxidation, and amino acid metabolism; i.e., TSN induced hepatocyte energy metabolism disorder. In conclusion, these data suggest novel mechanistic insights into TSN-induced liver injury on the upstream level and provide valuable proteins and energy metabolic targets for diagnosis and therapy in the clinic.