Optimization of Ultrasonic-assisted Extraction Technology of Ursolic Acid from Cornus officinalis and Its Antioxidant and Antibacterial Activities

In this work,orthogonal test of ursolic acid from Cornus officinalis was performed to determine the optimum process conditions by ultrasound-assisted extraction technology,based on the results of 7 single-factor experiments. The antioxidant activities were evaluated by the antioxidant tests of reducing power,DPPH·,·OH and lard.By agar diffusion and double dilution methods,the antibacterial activities of ursolic acid from Cornus officinalis were studied on 5 common food-borne pathogens. The results showed that the optimum process conditions of ursolic acid extraction from Cornus officinalis by ultrasound-assisted extraction technology were as follows:ultrasound extraction time 25 min,alcohol concentration 50%,ultrasonic power 225 W,the ratio of treatment to intermission 8 s/5 s,extraction times twice,extraction temperature 40 ℃,ratio of solid to liquid 1:25 (g/mL),under these conditions,the yield could reach 13.16%. Ursolic acid from Cornus officinalis showed good antioxidant and antibacterial activities. As the concentration of ursolic acid was 0.1 mg/mL,the percentage scavenging of DPPH· and ·OH being 88.1% and 68.6%. As the concentration was 0.75%,the antioxidant effect of ursolic acid from Cornus officinalis came to V_C whose concentration was 0.25%. The order of inhibition was Escherichia coli>Staphylococcus aureus>Bacillus subtilis>Proteus>Aspergillus niger. The MIC was as follows:6.26 mg/mL to Escherichia coli,12.5 mg/mL to Staphylococcus aureus and Bacillus subtilis,25 mg/mL to Proteus and Aspergillus niger.