Abstract: In order to find drugs with more effective bacteriostatic and bactericidal action,this study evaluated the antibacterial activity of Angelicae dahuricae on Staphylococcus aureus,Escherichia coli,Pseudomonas aeruginosa and Klebsiella pneumoniae by using agar plate perforation method and double dilution method.In particular,the influence of the drug on the quorum sensing of pathogenic bacteria was tested by investigating the virulence phenotype of Pseudomonas aeruginosa.The results showed that the extracts of Angelicae dahuricae had different inhibitory effects on four kinds of bacteria,and the inhibitory effect increased with the increase of extract concentration.Further separation found that trichloromethane,ethyl acetate and N-butanol extract had a certain inhibitory effect on four kinds of bacteria,of which the ethyl acetate extract was the best.The tests of four virulence phenotypes of Pseudomonas aeruginosa showed that Angelicae Dahuricae had the ability to inhibit the quorum sensing of this bacteria.To summarise,this research showed that the active components of Angelicae dahuricae could be used as a new type of Quorum Sensing inhibitor,which had the ability to inhibit many kinds of bacteria and would not produce drug resistance at the same time,it means that this traditional Chinese herb has a cheerful prospect in modern medicine.

Key words: Angelicae dahuricae, bacteriostasis activity, extractive, quorum sensing