Abstract: Objective: To investigate the effect of myricitrin from Diospyros lotus L. leaves on inducing apoptosis in human hepatocellular carcinoma HepG2 cells and its underlying mechanism. Methods: Cell viability was determined by the methyl thiazolyl tetrazolium assay. Laser confocal microscopy with Hoechst 33342 staining was used to observe cell morphology. Meanwhile, apoptosis, cell cycle arrest, intracellular reactive oxygen species (ROS) levels and monodansylcadaverine (MDC) mean fluorescence intensity in HepG2 cells were detected using a flow cytometer. Finally, Western blot was used to measure the expression levels of proteins associated with apoptosis and autophagy in HepG2 cells. Results: Myricitrin at concentrations of 10–200 μmol/L had no significant effect on human normal liver L-02 cells (P > 0.05), but could significantly reduce the survival rate of HepG2 cells (P < 0.05). Myricitrin could dramatically increase the apoptosis rate, ROS level, MDC mean fluorescence intensity and nuclear fluorescence intensity, and induce cell cycle arrest in the G2/M phase. In addition, myricitrin could up-regulate the expression levels of Bax, cytochrome c, Apaf-1, Caspase-9, Caspase-3, Beclin 1, Atg5 and LC3-II proteins significantly (P < 0.05), and down-regulate the expression levels of Bcl-2 and LC3-I proteins significantly (P < 0.05). Conclusion: Myricitrin has an anti-liver cancer effect, and its underlying mechanism is related to the activated mitochondrial-mediated apoptosis pathway, cell cycle arrest, increased intracellular ROS levels and promoted autophagy. These results lay a foundation for the development and application of myricitrin as a natural anti-hepatoma drug.

Key words: Diospyros lotus L. leaves; myricitrin; HepG2 cells; antitumor; mechanism