Objective: To investigate the effect of the water extract of Tetrastigmatis hemsleyani and the serum containing it on the proliferation in vitro. Method: The mice of clean grade were randomly assigned into 5 groups: high dose group (20 g·kg-1)

moderate dose group(10 g·kg-1)

low dose groups (5 g·kg-1)

positive control cyclophosphamide (CTX

5 g·kg-1) group and negative control group(distilled water). Every group was administered by intragastric administration 20 mL·kg-1 each

twice a day within 3 successive days. One hour after the last administration on third day

blood was collected from every decapitated mouse. The blood was centrifugalized for 20 min at 3 000 r·min-1after standing at 4 ℃. The separated serum was filtered to remove bacteria by 0.22 μm sepatate film at 56 ℃ after inactivated for 30 min and stored at -20 ℃ for later use. The suspensions of AGS cells in logarithmic growth phase digested by 0.25% tripsin were inoculated in 96 well culture plate with a cell density of 2.5×104/L. The different concentrations of the water extract of T. hemsleyani and the serum containing it were added into the culture after 24 h culture. MTT assay was used with determinating A value in the wavelength of 570 nm to evaluate the cell proliferation of the water extract of T. hemsleyani and the serum containing it for 48 h. Result: When the concentration of the water extract of T. hemsleyani was range from 1 g·L-1 to 40 g·L-1

a significant proliferation inhibiting (P<0.01) was shown and its 50% inhibition concentration(IC50) was 13.15 g·L-1. High

moderate and low dose treatment groups (20

10

5 g·kg-1) also significantly inhibited the proliferation of AGS cells and its IC50was 70.06 g·L-1. Both of the proliferation inhibitings were shown in dose-dependent manner. Conclusion: The water extract of T. hemsleyani can strongly inhibit the AGS cells proliferation.