桑叶茯砖茶总黄酮提取工艺优化及抗氧化活性

Optimization of the extraction process of total flavonoids from mulberry leaves Fu brick tea and their antioxidant activities

目的:优化桑叶茯砖茶总黄酮的乙醇提取工艺,并对其体外抗氧化活性进行研究。方法:通过单因素实验考察了乙醇浓度、液料比、提取时间、提取温度等对桑叶茯砖茶总黄酮得率的影响,在此基础上,采用响应面分析法优化提取工艺。以DPPH自由基清除率、.OH清除率、ABTS^+清除率和还原力等为指标,考察桑叶茯砖茶总黄酮的体外抗氧化活性。结果:最佳提取工艺条件为乙醇浓度为33%、液料比为25 mL/g、提取时间为2.3 h、提取温度为90℃,在该最佳条件下,桑叶茯砖茶总黄酮得率为2.37%。抗氧化实验表明,24μg/mL桑叶茯砖茶总黄酮对DPPH自由基清除率达89.8%,与Vc相当,ABTS^+的清除率为99.8%,清除效果较Vc好;0.28mg/mL桑叶茯砖茶总黄酮对.OH清除率达79.7%,而相同浓度Vc对.OH清除率为28.8%,显著低于桑叶茯砖茶总黄酮,0.28 mg/mL桑叶茯砖茶总黄酮还原力为1.263,和Vc接近。结论:该优选提取工艺稳定可行,桑叶茯砖茶总黄酮具有较强的抗氧化活性,为桑叶茯砖茶的开发和应用提供了依据。

Objective： To optimize ethanol extraction process of total flavonoids from mulberry leaves Fu brick tea and investigate its invitro antioxidant activity. Method： The effects of ethanol concentration, liquid-solid ratio, extraction time and extraction temperature on the yield of total flavonoids were investigated by single factor experiments. Response surface methodology was used to optimize the extraction process. The antioxidant activities were examined from the aspects of scavenging rate of DPPH, hydroxyl free radicals, ABTS~＋ and reducing power. Results： The optimum extraction process conditions were as follows： ethanol concentration was 33%, ratio of liquid to solid was 25 mL/g, extraction time was 2.3 h and extraction temperature was 90 ℃. Under the best condition, the yield of total flavonoids from mulberry leaves Fu brick tea was 2.37%. When total flavonoids concentration of the mulberry leaves Fu brick tea was 24 μg/mL, the rate of scavenging DPPH radicals was 89.8%, equivalent to Vc, and ABTS~＋scavenging rate was 99.8%, which was better than that of Vc. When total flavonoids concentration of the mulberry leaves Fu brick tea was 0.28 mg/mL, the rate of scavenging.OH radicals was 79.7%, while the same concentration of Vc on the.OH scavenging rate was 28.8%, significantly lower than that of mulberry leaves Fu brick tea, and the reducing power reached to 1.263 closing to Vc. Conclusion： The optimum extraction process is stable and feasible, the mulberry leaves Fu brick tea total flavonoids shows a relatively high antioxidant activity. It provides reference for development and utilization of mulberry leaves Fu brick tea.