赤水白茶总黄酮超声辅助提取工艺优化及其抗氧化活性

Optimization of Ultrasonic Assisted Extraction of Total Flavonoids from Chishui White Tea and Its Antioxidant Activity

采用响应面法优化赤水白茶中总黄酮的超声波辅助提取工艺,并分析其体外抗氧化活性。在单因素实验基础上,以甲醇浓度、液料比和提取时间为自变量,总黄酮提取量为响应值,采用Box-Behnken试验设计优化赤水白茶中总黄酮超声辅助提取工艺。结果显示,最佳提取工艺参数为:甲醇浓度69%,超声时间24 min,液料比102∶1 mL/g,该条件下赤水白茶总黄酮提取量可达243.50 mg RE/g,与模型理论预测值241.14 mg RE/g相近。体外抗氧化实验结果显示,赤水白茶总黄酮提取物对DPPH自由基和ABTS自由基清除率可达90.1%和99.8%,对亚铁离子螯合力达81.33%,其对DPPH自由基、ABTS自由基和亚铁离子的半数清除浓度(IC50)分别为0.082、0.027和0.781 mg/mL,且具有较好的还原力。响应面法优化赤水白茶总黄酮提取工艺稳定可靠,得到的总黄酮有较强的抗氧化活性,表明赤水白茶总黄酮有望成为一种良好的天然抗氧化剂。

In this study,ultrasound-assisted extraction of total flavonoids from Chishui white tea was optimized using response surface methodology(RSM),and their antioxidant activities were investigated.RSM was used to optimize the ultrasound-assisted extraction parameters for total flavonoids based on the single-factor test results.A Box-Behnken design(BBD)with three factors(methanol concentration,liquid-solid ratio and extraction time)was performed.The extraction yield of total flavonoids was taken as the response.The results showed that the optimized conditions for achieving the maximum yield of total flavonoids were 69% methanol concentration,24 min extraction time and 102∶1 mL/g liquid-solid ratio.Under these conditions,obtained yield value(243.50 mg RE/g)was in total agreement with value predicted by the model executed by BBD(241.14 mg RE/g).In vitro assays showed that the total flavonoids of Chishui white tea had strong free radical scavenging capacity and certain reducing power.The scavenging activities of DPPH free radicals,ATBS free radicals and the ferrous ions were up to 90.1%,99.8% and 81.33%,respectively,and the corresponding half maximal inhibitory concentration(IC50)were 0.082,0.027 and 0.781 mg/mL,respectively.Thus,it is stable and reliable to optimize the extraction method of total flavonoids from Chishui white tea.Furthermore,the total flavonoids obtained under optimum extraction conditions exhibited strong antioxidant activities,indicating that the flavonoids from Chishui white tea could be used as a potential source of natural antioxidants.