柚皮黄酮的超声辅助提取及其抗氧化性研究

以70% 乙醇为提取溶剂，采用超声辅助提取技术从柚皮中提取黄酮类化合物，利用二次旋转组合设计方法探讨柚皮黄酮的最佳提取工艺，建立了黄酮提取率与超声功率、超声时间和料液比之间的数学模型；通过化学方法考查了柚皮黄酮清除超氧阴离子自由基、DPPH 自由基以及羟自由基的能力。结果表明：黄酮提取率与各因素之间的关系可以表示为Y=0.5087+0.0311X1 － 0.0253X2 － 0.0289X3+ 0.0498X1 － 0.0238X1X3+ 0.0395X2+0.022X2X3 +0.0233X3，由此式得出柚皮黄酮的最佳提取条件为：超声功率1250W、超声时间10min、料液比1:30(g/ml)。经实验验证，柚皮黄酮的提取率可达0.734%，模型拟合度良好。抗氧化实验结果表明，柚皮黄酮具有较强的清除超氧自由基和DPPH 自由基的能力，其EC50(半抑制浓度)相应为0.0906、0.0161mg/ml，分别是VC 的1.9 倍和3.3倍；柚皮黄酮清除羟自由基的能力较弱，其EC50 为0.5649mg/ml，为VC 的15.5 倍。

Study on Ultrasonic-assisted Extraction and Antioxidation of Pomelo Peel Flavonoids

In this study, flavonoids were extracted from pomelo peel by ultrasonic extraction method using 70% ethanol as the solvent. The optimum extracting parameters were investigated with quadratic rotation combination design. The mathematical model including the rate of flavonoids extraction, ultrasonic power, ultrasonic time and the ratio of material to liquid was established. Scavenging effects of pomelo peel flavonoids on superoxide anion, DPPH, and hydroxyl radical were studied. The results showed that ultrasonic power, ultrasonic time and the ratio of material to liquid have significantly effects on the yield of pomelo peel flavonoids, and the regression quadratic equation is Y=0.5087+0.0311X1－0.0253X2－0.0289X3 +0.0498X1－0.0238X1X3+ 0.0395X2 + 0.022X2X3 + 0.0233X3, and the optimal conditions are attained through the regression equation as following: ultrasonic power 1250 W, ultrasonic time 10 min and the ratio of material to liquid 1:30 (g/ml). The extraction rate of flavonoids from pomelo peel is 0.734% through experiment and the mathematical model provids a good fit. Moreover, antioxidation experiments showed that flavonoids from pomelo peel have very strong scavenging capabilities for superoxide anion and DPPH free radical, their EC50 values are 0.0906 mg/ml and 0.0161 mg/ml respectively, and are approximately 1.9 times and 3.3 times as much as that of vitamin C respectively. The scavenging capability of pomelo peel flavonoids for hydroxyl radical is weaker than that of vitamin C, and its EC50 is 0.5649 mg/ml, 15.5 times as much as that of vitamin C.