[Cytotoxicity and underlying mechanism of evodiamine in HepG2 cells]

To investigate evodiamine (EVO)-induced hepatotoxicity and the underlying mechanism.

HepG2 cells were treated with EVO (0.04-25 μmol/L) for different time intervals, and the cell survival rate was examined by cell counting kit-8 (CCK-8) method. After HepG2 cells were treated with EVO (0.2, 1 and 5 μmol/L) for 48 h, the alanine transaminase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), alkaline phosphatase (ALP) activities and total bilirubin (TBIL) content of supernatant were detected. A multifunctional microplate reader was used to detect the intracellular superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in HepG2 cells to evaluate the level of cell lipid peroxidation damage. The interactions between EVO and apoptosis, autophagy or ferroptosis-associated proteins were simulated by molecular docking. The HepG2 cells were stained by mitochondrial membrane potential (MMP) fluorescent probe (JC-10) and annexin V-fluorescein isothiocyanate/propidium iodide (Annexin V-FITC/PI), and MMP and apoptosis in HepG2 cells were detected by flow cytometry. The protein expression levels of caspase-9, caspase-3, bile salt export pump (BSEP) and multidrug resistance-associated protein 2 (MRP2) were detected by Western blot.

The cell survival rate was significantly reduced after the HepG2 cells were exposed to EVO (0.04-25 μmol/L) in a time- and dose-dependent manner. The half maximal inhibitory concentration (IC50) of the HepG2 cells treated with EVO for 24, 48 and 72 h were 85.3, 6.6 and 4.7 μmol/L, respectively. After exposure to EVO (0.2, 1 and 5 μmol/L) for 48 h, the ALT, AST, LDH, ALP activities and TBIL content in the HepG2 cell culture supernatant, and the MDA content in the cells were increased, and SOD enzyme activity was decreased. Molecular docking results showed that EVO interacted with apoptosis-associated proteins (caspase-9 and caspase-3) better. JC-10 and Annexin V-FITC/PI staining assays demonstrated that EVO could decrease MMP and promote apoptosis in the HepG2 cells. Western blot results indicated that the protein expressions of cleaved caspase-9 and cleaved caspase-3 were upregulated in the HepG2 cell treated with EVO for 48 h. In contrast, the protein expressions of pro-caspase-3, BSEP and MRP2 were downregulated.

These results suggested that 0.2, 1 and 5 μmol/L EVO had the potential hepatotoxicity, and the possible mechanism involved lipid peroxidation damage, cell apoptosis, and cholestasis.