响应面法优化辣木叶总黄酮提取工艺及其抑菌性研究

Extraction Optimization and Antibacterial Activity of Total Flavonoids in Moringa oleifera Leaves by Response Surface Methodology

为提高辣木资源利用率,对辣木叶总黄酮的提取工艺进行优化,并测定辣木叶总黄酮的抑菌能力。以超声处理功率、超声辅助提取时间、乙醇体积分数、液料比为考查因素,以辣木叶总黄酮提取率为考查目标,在单因素试验的基础上进行Box-Behnken响应面试验设计,优化确定辣木叶总黄酮的最适提取工艺;同时,采用牛津杯法和二倍稀释法测定辣木叶总黄酮对4种供试菌的抑菌圈直径和最低抑菌浓度,考查辣木叶总黄酮的抑菌活性。研究结果表明,辣木叶总黄酮超声辅助提取最佳工艺为超声功率400 W、超声时间35 min、乙醇体积分数65 %、液料比41 ∶ 1 (mL/g),此时辣木叶总黄酮提取率达7.64 %。抑菌研究结果表明,最优工艺条件下提取的辣木叶总黄酮对白色假丝酵母、金黄色葡萄球菌、枯草芽孢杆菌、大肠杆菌具有不同程度的抑菌作用,白色假丝酵母、大肠杆菌、金黄色葡萄球菌的最低抑菌浓度(minimum inhibitory concentration, MIC)为2.05 mg/mL,枯草芽孢杆菌的MIC为4.10 mg/mL。

To increase the utilization rate of moringa, the extraction conditions of total flavonoids in Moringa oleifera leaves were optimized and the antibacterial activity was studied. Using extraction efficiency of total flavonoids as evaluation index, the ultrasonic power, the time of ultrasonic-assisted treatment, ethanol concentration and liquid/solid ratio were investigated through single factor test and Box-Behnken response surface methodology to acquire the optimum extraction process. Meanwhile, the antibacterial activity of total flavonoids was evaluated through Oxford-cup test and serial two-fold dilution method by measuring the inhibition zone and minimal inhibitory concentration (MIC) regarding four tested microorganisms. The results indicated that the optimum extraction conditions were as follows: ultrasonic power was 400 W, the time of ultrasonic-assisted treatment was 35 min, ethanol concentration was 65 %, liquid/solid ratio was 41 ∶ 1 (mL/g),the extraction efficiency of total flavonoids reached 7.64 %. The bacteriostatic study showed that the obtained total flavonoids had antibacterial capacity towards Candida albicans, Staphylococcus aureus, Bacillus subtilis and Escherichia coli of varying degrees, with MIC of 2.05 mg/mL for C. albicans, E. coli and S. aureus, and 4.10 mg/mL for B. subtilis.