In vitro Cytotoxicity and Apoptosis-inducing Activity of Quercus infectoria Extracts in HeLa Cells

Background: Quercus infectoria galls (QI) extracts were previously reported to have cytotoxicity effects towards human cervical cancer cells, HeLa. However, the underlying molecular mechanisms of the extracts have been poorly determined. Objective: The present study was undertaken to examine the effect of ethyl acetate extracts of QI (EAQI) on cell cytotoxicity and induction of apoptosis in HeLa cells. Materials and Method: The in vitro cytotoxicity was investigated by using the MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide] assay and the OD values were read at 570 nm. Meanwhile the induction of apoptosis was measured by using acridine orange and propidium iodide (AO/PI) staining, flow cytometry analysis of annexin V/PI staining and cell cycle distribution. Results: MTT assay showed that EAQI exhibited cytotoxicity effect on HeLa cells with IC₅₀ of 11.50 ± 0.50 μg/ml. HeLa cells underwent apoptosis in response to EAQI treatment, demonstrated by an increase in the percentage of apoptotic cell stained with AOPI from 1.00% to 10.33% compared to untreated cell population (p<0.05) at 72 hours of treatment. The evidence of early apoptosis in treated cells were also observed in annexin V/PI staining. Furthermore, an increase of cell population in sub G0/G1 phase revealed that apoptosis as the mode of cell death in HeLa cells treated with EAQI. Conclusion: These findings indicated that EAQI significantly inhibits HeLa cell growth through induction of apoptosis. Further studies are needed to confirm the mechanism of cell death by expression of apoptotic cascade in HeLa cells treated with EAQI.