正交试验优化黑果悬钩子茎、叶总黄酮的提取纯化及其抗氧化活性

Extraction,Purification and Antioxidant Activity of Total Flavonoids from the Leaves and Stems of Rubus caesius L.

利用单因素试验和正交试验优化了黑果悬钩子(Rubus caesius?L.)茎和叶总黄酮的提取工艺,通过清除DPPH自由基、ABTS+·的方法测定了黑果悬钩子茎和叶的抗氧化活性。优化的总黄酮提取工艺为:提取温度80℃、提取时间70 min、乙醇溶液体积分数60%、料液比1∶90(g/m L)。通过比较AB-8等14种大孔树脂对黑果悬钩子茎、叶总黄酮的吸附分离效果,从中筛选出AB-8大孔树脂是理想的吸附剂。通过单因素试验,确定AB-8大孔树脂对黑果悬钩子总黄酮分离纯化的最优工艺为:上样流速1?m L/min、上样液总黄酮质量浓度0.32?mg/m L、上样体积80?m L,吸附饱和平衡后,以40?m L?60%乙醇溶液1.5?m L/min的流速动态洗脱。经AB-8大孔吸附树脂纯化后,提取液的总黄酮含量和抗氧化能力显著提高,叶和茎总黄酮含量为纯化前的1.4倍和2.4倍,叶和茎的的ABTS+·清除能力分别为纯化前的1.7倍和2.5倍,DPPH自由基清除能力分别为纯化前的1.7倍和2.6倍。这些结果表明:黑果悬钩子叶和茎均具有较高的总黄酮含量和明显的抗氧化活性,是潜在的天然抗氧化剂资源。

The extraction of flavonoids from the leaves and stems of Rubus caesius L. was optimized by single factor experiments and an orthogonal array design. Antioxidant activity of flavonoids extracts was determined by 2,2＇-azinobis-（3- ethylbenzthiazoline-6-sulphonate） （ABTS）, 1,1-dipbenyl-2-picrylhydrazyl （DPPH） radical scavenging assays. The optimal extraction conditions for total flavonoids were determined as follows： 80 ℃, 70 rain, and 60% ethanol as the extraction solvent with a solid-to-liquid ratio of 1：90 （g/mL）. By comparing the adsorption and separation efficiencies of flavonoids with 14 different macroporous resins, AB-8 resin was selected as the most efficient adsorbent as it had the best adsorption and desorption capacity for flavonoids from R. caesius L. By single factor experiments, the optimal purification conditions for crude flavonoids from R. caesius L. leaves and stems were established as foUows： sample loading flow rate, 1 mL/min; flavonoids concentration of sample, 0.32 mg/mL; sample volume, 80 mL; desorption solvent, 40 mL of 60% ethanol; and desorption flow rate, 1.5 mL/min. After being separated and purified by AB-8 resin, both total flavonoids content and total antioxidant capacity were significantly improved. The total flavonoids contents from leaves and stems were increased by 1.4 and 2.4 times, the ABTS radical scavenging rates by 1.7 and 2.5 times, and the DPPH radical scavenging rates by 1.7 and 2.6 times, respectively. These results demonstrate that the leaves and stems of R. caesius L. have high flavonoids contents and antioxidant activity, and can be potential sources of natural antioxidants.