超声-微波辅助提取橄榄苦苷及抗氧化活性研究

Study on Extraction and Antioxidant Activity of Oleuropein from Olive Leaves by Synergistic Ultrasonic/Microwave Assisted

以油橄榄叶为原料,研究超声-微波协同提取(UMAE)橄榄苦苷的最佳工艺。选用乙醇作为提取剂,并运用紫外-可见光谱差减法定量分析橄榄苦苷含量。通过单因素试验,选择提取时间、微波功率、固液比、温度和乙醇体积分数考察其对提取橄榄苦苷含量的影响,进行Plackett-Burman (PB)试验,得到超声-微波协同提取的关键工艺参数,并进行响应面分析(RSA)。通过体外抗氧化试验,考察橄榄苦苷对DPPH、ABTS+和羟自由基的清除率效果。结果表明:提取时间18 min、微波功率475 W、固液比1︰45 g/mL、温度40℃、乙醇体积分数60%是超声-微波协同提取的最佳提取条件,此时橄榄苦苷含量为68.91±0.64 mg/g。DPPH自由基清除率的半抑制浓度(IC50)是0.035±0.001 mg/mL,羟自由基清除率的半抑制浓度(IC_(50))是0.004±0.010 mg/mL, ABTS自由基清除率的半抑制浓度(IC_(50))是0.058±0.003 mg/mL,表明油橄榄叶提取液具有较强抗氧化作用。

The optimum process for ultrasonic-microwave synergistic extraction(UMAE) of oleuropein was investigated using olive leaves as raw material. Ethanol was selected as the extraction solvent, and the content of oleuropein was determined using differential subtraction method of UV-Vis spectroscopy. The effects of the independent variables time,microwave power, solid-liquid ratio, temperature and ethanol concentration on the content of oleuropein were investigated through one-way experiments. The Plackett-Burman(PB) test was performed to obtain the key process parameters in the ultrasound-microwave synergistic extraction method, and finally, response surface analysis(RSA) was performed. On this basis, the effect of oleuropein on the scavenging rate of DPPH, ABTS+ and hydroxyl radicals was examined by in vitro antioxidant test. The results showed that the extraction time of 18 min, microwave power of 475 W, solid-liquid ratio of 1︰45 g/mL, temperature of 40 ℃, and ethanol concentration of 60% were the optimal condition for the ultrasound-microwave synergistic extraction, at which the content of oleuropein was 68.91±0.64 mg/g. The semi-inhibitory concentration(IC_(50)) for the scavenging rate of the DPPH radicals was 0.035±0.001 mg/mL, the semi-inhibitory concentration(IC_(50)) for ABTS radical scavenging was 0.058±0.003 mg/mL, and the semi-inhibitory concentration(IC_(50)) for hydroxyl radical scavenging was 0.004±0.010 mg/mL. The study showed that olive extract obtained from olive leaves had strong antioxidant effect.