Optimization of Ultrasonic Assisted Extraction for Total Flavonoids from Ginkgo biloba Leaves and Its Scavenging Capacity on Hydroxyl Free Radicials

In the present study,Ginkgo biloba leaves were used as the research object,and the extraction process of total flavonoids in Ginkgo biloba leaves was optimized by ultrasound-assisted ethanol extraction. Based on single factor test analysis,the total flavonoids yield was set as the response value. Four factors which affect total flavonoids extraction from Ginkgo biloba leaves were designed and optimized by Box-Behnken experiment,so as to analyze the effect of ethanol concentration,material-to-liquid ratio,extraction temperature and extraction time on the yield during the extraction process. And the scavenging rate of hydroxyl radicals was also studied. The results showed that the optimum extraction technology of total flavonoids from Ginkgo biloba leaves were ethanol concentration 81%,material-to-liquid ratio 1∶26 g/mL,extraction temperature 75 ℃ and extraction time 51 min. The yield of total flavonoids could be up to 3.58% under the optimal condition. The total flavonoids extracted from Ginkgo biloba leaves had higher scavenging effect on hydroxyl radicals than V_C,and its antioxidant capacity had a positive correlation with the concentration. The study could provide theoretical basis for the extraction,utilization and development of total flavonoids from Ginkgo biloba leaves.