复合酶辅助超声提取西藏芜菁总黄酮工艺优化及抗氧化活性分析

以西藏芜菁为原料，研究复合酶辅助超声法提取芜菁中总黄酮的最佳工艺条件及其抗氧化活性。以总黄酮得率为考察指标，通过Plackett-Burman实验筛选出对得率影响最显著的三个因素:复合酶配比、料液比及超声功率。随后通过响应面法优化芜菁总黄酮的提取工艺，同时通过DPPH自由基和ABTS+自由基清除实验评估了芜菁总黄酮的抗氧化活性。结果表明，复合酶辅助超声法提取芜菁总黄酮的最佳工艺条件为:复合酶配比为1.9:1 g/g，复合酶用量为2%，料液比为1:38 g/mL，乙醇浓度为75%，酶解温度为50℃，酶解时间为55 min，超声功率为204 W，超声时间为60 min，在此条件下总黄酮得率达到最大值1.458%。抗氧化实验结果表明芜菁总黄酮对DPPH自由基清除的IC₅₀为185.6 μg/mL，对ABTS+自由基清除的IC₅₀为164.3 μg/mL，说明芜菁总黄酮具有体外抗氧化活性。综上，本研究得到了复合酶辅助超声法提取芜菁总黄酮的最佳工艺条件，且提取得到的芜菁总黄酮具有较强的抗氧化活性，为西藏芜菁的开发及利用提供了一定的科学依据。

Enzyme-assisted Ultrasonic Extraction of Total Flavonoids from Brassica rapa L.Optimization and Its Antioxidant Activity Analysis

In this study,the extraction of total flavonoids in Tibetan turnip by enzyme-assisted ultrasonic technology and its antioxidant activity were studied.We used the yield as an indicator,and the Plackett-Burman experiment was conducted to screen out the three factors that had the most significant effect on yield:Compound enzyme ratio,material-liquid ratio and ultrasonic power.The extraction of total flavonoids in turnip was then optimized by response surface methodology.While the antioxidant activities of total flavonoids were evaluated by DPPH and ABTS⁺free radical scavenging experiments.The results showed that the optimal conditions for the extraction of total flavonoids from turnip are:The compound enzyme ratio was 1.9∶1 g/g,the compound enzyme dosage was 2%,the material-liquid ratio was 1∶38 g/mL,the ethanol concentration was 75%,the enzymolysis temperature was 50℃,the enzymolysis time was 55 min,the ultrasonic power was 204 W,and the ultrasonic time was 60 min.Under these conditions,the maximum yield of total flavonoid was 1.458%.The results of anti-oxidation experiment showed that the IC₅₀ of DPPH free radical scavenging was 185.6μg/mL,and was 164.3μg/mL of ABTS⁺free radical scavenging,which indicated the total flavonoids of turnip had antioxidant activity in vitro.In summary,this study showed the conditions for the extraction of total flavonoids in turnips by enzyme-assisted ultrasonic method,and the total flavonoids had strong antioxidant activity,which would provide scientific basis for the future development and utilization of Tibetan turnips.