Abstract:Objective: To investigate the contents of glycyrrhizic acid in hejian decoction (mixed the traditional Chinese herbs together, then boiling them with water) and the fenjian decoction (boiling the single traditional Chinese herb with water separately, then mixed the abstracts) of Sanaotang (composed of Ephedra sinica, Prunus armeniaca and Glycyrrhiza uralensis) and to compare with their anti-bacterial activities in vitro. Method: A HPLC method was established with a Agilent Zorbax SB-C18 column (4.6 mm×250 mm, 5 μm), a mobile phase of acetonitrile-0.2% acetic acid solution (35∶65), a flow rate of 1 mL·min-1 and a detection wavelength of 254 nm in order to determine the contents of glycyrrhizic acid minimal bacterial inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) antagonized the common bacteria in different decoctions were measured in vitro by employing dilution method. Result: The average content of glycyrrhizic acid of the hejian decoction was higher than that of the fenjian decoction. The hejian decoction could display the inhibitory bactericidal activity to Aeruginosus bacillus, but the fenjian decoction could not. And to Staphylococcus aureus, the inhibitory bactericidal activity the hejian decoction was slightly stronger than that of the fenjian decoction. Conclution: Comparing with that of the fenjian decoction, the content of glycyrrhizic acid of the hejian decoction was higher and the anti-bacterial activities was stronger.