Structure analysis of ethyl ferulate from Rubus corchorifolius L.f. leaves and its inhibitory effects on HepG2 liver cancer cells

The tender leaves of Rubus corchorifolius L. f. (R. corchorifolius) have been made into herbal tea for relieving coughs in East and Southeast Asia from ancient times. Herein, we obtained an ethyl acetate extract from R. corchorifolius leaves and isolated a major bioactive compound within. Structural analysis of the isolated compound was performed by spectroscopic methods and the compound was identified as ethyl ferulate. Effect of ethyl ferulate on the growth and proliferation of human liver cancer HepG2 cells and normal human liver LO2 cells was determined by MTT assay. We found that ethyl ferulate significantly suppressed the cell proliferation of HepG2 cells (IC50 26.4 mu M), while it did not cause cytotoxicity on LO2 cells. In addition, flow cytometry analysis demonstrated that ethyl ferulate inhibited HepG2 cell growth via inducing cellular apoptosis. Specifically, ethyl ferulate reduced the electrical potential of the mitochondrial membrane and increased the concentration of calcium ions inside cells. Moreover, these changes were accompanied by increases in the expression of the proapoptotic proteins, such as cleaved caspase-3 and Bax. In contrast, cell morphology and growth of LO2 cells remained unaffected. In conclusion, for the first time, our observations demonstrated that ethyl ferulate possesses great potential as an effective and safe antitumor agent for cancer chemoprevention in humans.