Abstract: The extraction process of total tannins from Magnolia officinalis was optimized by response surface design and further purified. The results showed that the best extraction process for total tannins from Magnolia officinalis was the ratio of material to liquid of 1∶13, extraction time of 100 min, ethanol concentration of 80% and ultrasonic power of 80 W. The total tannins extracted from Magnolia officinalis was 0.181 0 mg/g, which was not far from the theoretical value of 0.188 8 mg/g. The optimum purification process of total tannins from Magnolia officinalis by gelatin solution precipitation was studied by an orthogonal test. When the specific gravity of concentrated solution was 1.5 mg/mL, the concentration of gelatin solution was 4%, and the amount of gelatin solution added was 8 mL/100 mg, the total tannins extracted from Magnolia officinalis was 2.743 mg/g. The antibacterial activities of total tannins against Staphylococcus aureus and Escherichia coli were compared by the minimum inhibitory concentration method. The results showed that the total tannins from Magnolia officinalis had certain antibacterial activity.

Key words: Magnolia officinalis Rehd. et Wils., total tannins, response surface methodology, orthogonal test, antibacterial activity