Aqueous Extract of Cornus officinalis Alleviate NAFLD via Protecting Hepatocytes Proliferation through Regulation of the Tricarboxylic Acid Cycle

Ethnopharmacological relevance: Cornus officinalis (CO) has been widely used as Chinese herbal medicine and has a good clinical efficacy in liver disease. In particular, it has a significant therapeutic effect on metabolic liver disease. However, systematic pharmacological studies on its hepatoprotective effect on non-alcoholic fatty liver disease (NAFLD) are lacking.

Aim of the study: We investigated the impact of Cornus officinalis extract (COE) on two mouse models of NAFLD, screened the potential mechanisms of action by using metabolomics assays, and explored the protective effects on hepatocyte proliferation by regulating glutamate metabolism and tricarboxylic acid (TCA) cycle.

Methods: The main components of COE were identified by high performance liquid chromatograph (HPLC). Male C57BL/6J mice were subjected to construct carbon tetrachloride (CCl₄) or methionine choline deficient (MCD) induced NAFLD mice. Liver function and lipid biochemical indicators were detected using commercial assay kits. Masson staining, Western blot, and immunohistochemistry analyses were used for assessing hepatic injury and fibrosis. LC-MS non-targeted analysis was performed using the 1290 Ultra-High Performance Liquid Chromatograph System and the 6540 Q-TOF Mass Spectrometry. Palmitic acid (PA) induced L-02 cell model was established. The mediators in glutamate metabolism and TCA cycle were assessed by assay kits.

Results: In vivo experiments validated that COE significantly improved liver function in NAFLD mice, reduced lipid accumulation, and alleviated pathological damage and liver fibrosis. The non-targeted metabolomics analysis combined with Ingenuity Pathway Analysis (IPA) located glutamate metabolism and the downstream TCA cycle as potential mechanisms of COE, which was further confirmed in NAFLD model mice and PA-induced L-02 cells. Finally, we confirmed that COE could promote mitochondrial energy supply by remodeling the homeostasis of the TCA cycle, thereby enhancing hepatocyte proliferation.

Conclusions: This study demonstrated that COE could significantly improve CCl₄ or MCD-induced NAFLD by promoting hepatocyte proliferation. These results highlighted the potential of COE as leads for the development of innovative treatments for NAFLD.