[Studies on flavonoids extraction technology from Glycyrrhiza inflata and their bacteriostatic activities].

Objective: To study the extraction technique for the flavonoids from Glycyrrhiza inflata and their bacteriostatic bioactivities.

Methods: It was investigated about comparison of extraction methods such as ultrasonic-assisted extraction (UAE), enzymatic extraction (EE), whisk extraction (WE) and repeat freeze-dissolve extraction (FDE). The UAE conditions were optimized by orthogonal array. The bacteriostatic effect was studied using doubling dilution.

Results: The UAE was the most effective method and the optimal UAE conditions were adding 20-fold ethanol (30% v/v), extracting for two times, 20 min each time. Futhermore, the minimal inhibitory concentrations (MIC) of the flavonoids against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis were 0.03125, 0.03125, 0.125, 0.03125 mg/ml respectively.

Conclusion: UAE is suitable for fast and effective extraction of flavonoids. The flavonoids have obvious bacteriostatic bioactivities against microorganisms mentioned above.