Abstract: The total saponin was isolated from Rohdea chinensis rhizome through the ethanol water bath heating extraction method.The influences of ethanol concentration,liquid to material ratio,extraction time and extraction temperature on the yield rate of the total saponin were investigated.On the basis of single factor test,the orthogonal test was used to optimize the extraction process.The optimal extraction conditions of total saponins from the rhizome of Rohdea chinensis are as follows:material-liquid ratio 1∶30 (g∶mL),ethanol concentration 60%,extraction time 60 min,and extraction temperature 80 ℃.Under these extraction conditions,the total saponin yield of Rohdea chinensis was 17.46%.The results of the antibacterial activity test showed that the total saponins in the rhizome of the Rohdea chinensis had inhibitory effects on Escherichia coli,Staphylococcus aureus,Candida albicans,and the inhibitory activity on Staphylococcus aureus was the best,with the diameter of the inhibition circle 12 mm at a concentration of 5 g/L.

Key words: rhizomes of Rohdea chinensis, total saponins, extraction process, antibacterial activity, orthogonal test