Mechanism of Bakuchiol-induced liver injury in mice by transcriptomic, proteomic, and metabolomic analyses

<b>Backgrounds:</b> Existing research has confirmed that <i>Psoralea corylifolia L.</i>, i.e., Fructus Psoraleae (FP), results in hepatotoxicity. In our previous study, Bakuchiol (Bak) was indicated as one of the main toxic components in FP. However, the exact underlying mechanism of how toxic components contained in FP react remains unclear.<b>Methods</b><b>:</b> In this study, toxicity was evaluated initially in ICR mice to confirm the hepatotoxicity of Bak. Subsequently, the transcription of genes, the up-regulated expression of proteins and changes of metabolite spectrum in a biological system in accordance with system pharmacology and multi-omics profiling strategy were investigated to reveal its toxic mechanism.<b>Results</b><b>: </b>Results show an obvious Bak-induced hepatotoxicity in our experiment. The mice administrated with Bak for 4 weeks exhibited significantly increased liver weight, liver/body weight ratio, and liver/brain weight ratio. To be specific, the liver/brain weight ratio was increased by 17.66%. The significant apoptosis of hepatocytes and hollow atrophy of nuclei were indicated by the TUNEL assay on the hepatotoxicity of Bak in mice. The mice administrated with Bak for 4 weeks showed significant apoptosis of hepatocytes, and the stained nucleus was hollow. In general, the pathways associated with Bak-induced hepatotoxicity were associated with bile secretion, primary bile acid synthesis, fatty acid biosynthesis, PPAR signaling pathway, fatty acid metabolism, and biosynthesis of unsaturated fatty acids. Moreover, 19 differentially expressed genes and proteins significantly associated with the above lipid metabolic process were screened, which were significantly associated with lipid metabolism. Next, 18 different metabolites associated with lipid metabolism were selected, which were primarily concentrated in glycerophospholipids, fatty acids, and bile acids. Glycerophospholipid metabolism disorder was outstanding and induce apoptotic process, leading to liver injury, which is consistent with previous characterization.<b>Conclusion</b><b>:</b> The results analyzed and screened using multi-omics displayed consistent trends with those obtained in the hepatocyte phenotype that was tested by organ weights, relative organ weights, histopathological changes, and TUNEL assay. The study initially employed system pharmacology and 3-omics profiling strategy to propose Bak-induced liver injury in mice and elucidate the mechanism, providing insights into improved safety assessment of oral administration of FP.