Objective: The total flavonoids of Broussonetia papyrifera(TFBP ) was investigated for its antitumor activity and induction of apoptosis in vitro

using human HepG-2 hepatocellular carcinoma cell line. Method: The hepatocellular carcinoma HepG-2 cells in logarithmic phase of growth were randomly divided into drug group and control group

with the concentration of 3

6

9

12 g·L-1 TFBP in hepatocellular carcinoma HepG-2 cells intervention durations were 24

48

72 h accordingly. The viability of HepG-2 cells was measured by MTT. Morphology of cell apoptosis was observed by Hoechst 33342 fluorescence staining. The protein expression of B cell lymphoma/leukemia-2(Bcl-2) and Bcl-2 associated X protein(Bax) was analyzed by immunocytochemical method(SP). Result: TFBP inhibited the growth of cells and caused apoptosis significantly. The suppression was both in a time-and dose-dependent manner. When HepG-2 cells were treated with the concentration of 9

12 g·L-1 TFBP in 72 h

the inhibition rate can be achieved 52.46%

64.72% respectively. Compared with control group

there has significant difference (P<0.01). When HepG-2 cells.were treated with the concentration of 9

12 g·L-1 TFBP in 48 h

the typical apoptotic body can be observed under the fluorescence microscope.The increase of caspase-3 activity induced by TFBP showed a concentration-efficiency.TFBP down-regulated the Bcl-2 expression and up-regulated the Bax expression. The ratio of Bcl-2/Bax was evident decrease. Conclusion: TFBP has apparent inhibition and apoptosis-inducing effect on HepG-2 cells. TFBP may induce apoptosis via down-regulating Bcl-2 expression

up-regulating of Bax expression

decreasing the ratio of Bcl-2/Bax and enhancing caspase-3 activities in HepG-2 cells.