| Poyang Lake, China’s largest freshwater lake abounds with wild plants and fisheries resources. Artemisia Selengensis Turcz, a featured seasonal vegetable, especially with large growth area, high yield, and unique fragrance and of high nutritional value, is deeply enjoyed by everyone. The tender stems are eaten but the rest are usually thrown away. Scientific research shows that Artemisia Selengensis Turcz has rich natural active ingredients in its leaves and old stems, such as flavonoids and polysaccharides, with a wide range of pharmacological functions such as antioxidant, anti-aging and anti-virus, thus it is an important source of raw materials for natural health care products.In this thesis, ultrasonic wave was used to extract flavonoids from Artemisia Selengensis Turcz leaves, studying optimum process of ultrasonic assisted extraction, separation, purification and determining antioxidant activity; adopting cellulose assisted extraction to prepare polysaccharides from old stems.Optimum process and antioxidant activity were investigated. Opened up new avenues for the comprehensive utilization of high-value leaves and old stems resources from Artemisia Selengensis Turcz.Main contents and conclusions are summarized as follows:(1)Effects of different extraction solvents on the yield of total flavonoids from wild Artemisia Selengensis Turcz were studied. The result showed extraction with50%ethanol demonstrated the highest concentration of total flavonoids,335.02±10.63μg/mL.And study different extraction methods effects on total flavonoids yield. The results showed that ultrasonic assisted extraction brought the highest content of total flavonoids,37.76±0.45μg/mg.(2)Choosing rutin as matched control, the content of total flavonoids was measured with direct method and aluminum nitrate chromogenic method.The result showed that after aluminum nitrate chromogenic reaction, the maximum absorption wave lengths of rutin and flavonoids were basically consistent, and rutin standard curve had a good linearity and precision; So it could be used for the determination of flavonoids.(3)The process of ultrasound assisted extraction of flavonoids was optimized by response surface method.The result showed the optimum extraction parameters were: the ratio of liquid to solid,45mL/g;the concentration of ethanol,71.2%; ultrasonic time,39.5min;extraction temperature,72℃and extraction twice.Under this condition, the yield of flavonoids was3.63%。(4)The abilities of static adsorption and desorption performance of six macroporous adsorptive resins to flavonoids were studied.The result dispalyed LK001had the best adsorption ability to flavonoids, and could well separate and purify flavonoids.The purity of flavonoids was above45.26%.(5)Effects of crude flavonoids extracts and purified sample on scavenging free radicals were compared.The study showed that both crude and purified flavonoids solution had good capacities of scavenging free radicals. Removal efficiency of crude flavonoids extracts was IC50(DPPH-)=42.48mg/L, IC50(O2-·)=0.71mg/mL, IC50(·OH)=0.59mg/mL; that of purified flavonoids solution was IC50(DPPH-)=34.75mg/L, IC50(O2-·)=0.64mg/mL, IC50(·OH)=0.54mg/mL. The antioxidant capacity not only had a great relationship with the purity and concentration of flavonoids solution, but also with the types of free radicals.(6)The cellulose assisted extraction process of polysaccharides was optimized through orthogonal experiments. The result indicated that the optimal conditions were pH,6.0; extraction temperature,50℃extraction time,2hours; the amount of cellulose,1.5%(of dry matter proportion); under these conditions the polysaccharides had the highest yield of4.77%.(7)The abilities to scavenge radicals of the crude and refined polysaccharides from old stems were compared. Removal efficiency of crude polysaccharide is IC50(DPPH-)=4.31mg/mL, IC50(O2-·)=15.19mg/mL, IC50(·OH)=6.93mg/mL.That of refined polysaccharides is IC50(DPPH·)=2.61mg/mL, IC50(02-·)=6.29mg/mL, IC50(·OH)=4.63mg/mL.The result indicated that both polysaccharides had good capacity of scavenging free radicals,and the antioxidant capacity was proportional to polysaccharides concentration. At the same concentration the refined polysaccharides solution showed a better antioxidant capacity than crude solution, but there were still large differences comparing to Vc. |
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