Objective: To explore the effect of water extract of Clematidis Radix et Rhizoma on proliferation of HTh74Rdox cells and its mechanism. Method: HTh74Rdox cells were treated by different concentrations of water extract of Clematidis Radix et Rhizoma

in order to observe morphological changes and apoptosis of HTh74Rdox cells. methylthiazolyldiphenyl-tetrazolium bromide (MTT) was used to test the inhibitory effect of water extract of Clematidis Radix et Rhizoma on proliferation of HTh74Rdox cells. The cell cycle change and the cell apoptosis rate were further detected by flow cytometry; Western blot was used to measure the expressions of cleaved-Caspase-3

Caspase-3

Bcl-2 and Bax. Result: Zedoary oil played a significant role in inhibiting the growth of HTh74Rdox cells. The combination of water extract of Clematidis Radix et Rhizoma and adriamycin could reduce the average dose of Adriamycin. Water extract of Clematidis Radix et Rhizoma significantly increased the percentage of cleaved-Caspase-3/Caspase-3 and Bax/Bcl-2. Conclusion: Water extract of Clematidis Radix et Rhizoma can inhibit the growth of HTh74Rdox cells. And its possible mechanism may be correlated with the increase of cleaved-Caspase-3/Caspase-3 and Bax/Bcl-2 ratio. Water extract of Clematidis Radix et Rhizoma combined with chemotherapy drug has the effect in reducing toxicity and increasing efficiency.