Optimization Of Extraction Condition And Evaluation Of Antioxidant Activities Of The Total Flavonoids In Dendrobium Fimbriatum Hook

With the improvement of people’s life, more functions of the modern landscape have been demanded. In addition to the traditional recreation, ornamental function, landscape is also responsible for maintaining public health. From the rise of construction to the "healthcare landscape gardening therapy", which is a reflection that people have regarded that physical needs are as important as the mental needs during the construction of a garden. As the fundation of the health care type gardens, plants with health care function of landscape have attracted more and more attention.In Orchidaceous plants, the Dendrobium is a large genus. They have been widely used in gardens because of their bright and abundant colors, beautiful gestures, long florescence, and storage and cut resistance. Besides, Dendrobium also have various health care functions, so they always been called fairy grass. The Dendrobium fimbriatum Hook, as one of the 5 species of Dendrobium with medicinal value which are recorded in the Chinese medicinal plants (2005 Edition), is more significant than other Dendrobium species. But the medicinal value development and utilization of the flavonoids which is an important secondary metabolite of Dendrobium fimbriatum Hook are still in the initial stage. Therefore, the potential of the Dendrobium flavonoids is worthy to be widely developed.In this experiment, we studied on the optimization of extraction conditions of flavonoids from Dendrobium fimbriatum Hook, their purification process and their antioxidant activities in vitro. Alcohol re fluxing extraction was chose as the only extract method in the experiment and by doing the single factor test, extraction temperature, ratio of liquid to raw material and the concentration of ethanol were found had the significant influence on flavonoids extracting. By the Box-Behnken Design’s experiments, we got the ordinary data, and response surface methodology was used to optimize the extraction condition and the optimal condition was that: extraction temperature was 87℃, ratio of liquid to raw material was 34 (mL/mg) and the concentration of ethanol was 73%(v/v), and the predicted yield of extracted was 4.63mg/g.The average experimental total flavonoids yield under the optimum conditions was found to be 4.52±0.02 mg/g, which agreed with the predicted value of 4.63mg/g.The evaluation of antioxidant activity in vitro contains reducing power assaying, DPPH radical scavenging assaying, ABTS radical scavenging assaying and Hydroxyl radical scavenging assaying. The results revealed that scavenging effect to ABTS radicals and DPPH radicals are significant.When the concentrations of total flavonoids sample got to 0.8mg/mL, the clearance rate of ABTS radicals can get to 100% and the maximum clearance rate of DPPH radicals can get to 83.68 when the concentration increased to 3.2mg/mL.By having done those anti-oxidant tests in vitro we can knew that the total flavonoids in Dendrobium fimbriatum Hook are novel potential antioxidant.Dendrobium fimbriatum Hook flavonoids extraction was purified by Macroporous Resin (AB-8).the resin was washed with l00mL of distilled water to remove water-soluble impurities, then the flavonoids was eluted from the macroporous resin with 80% ethanol.collected the eluent and concentrated and dryed the eluent used vacuum drying method. The pureness of the flavonoids extraction was 3.96%. After the flavonoids extraction was purified by Macroporous Resin (AB-8), the pureness of it was improved to 10.40%. That reflected the AB-8 has a significant effect on purifing the flavonoids extrction.The evaluation of antioxidant activity of flavonoids sample in vitro was also contains reducing power assaying, DPPH radical scavenging assaying, ABTS radical scavenging assaying and Hydroxyl radical scavenging assaying.After purified, the antioxidant activity of flavonoids sample was more significant than before, but was still lower than Vc. The reducing power of the flavonoids sample was increased with the rose of its concentration. When the concentration improved to 6.4mg/m, the reducing power of it can get to 1.975. The scavenging effect to ABTS radicals of flavonoids sample got the highest point (100%) when the concentration increased to 0.4 mg/mL. After puried, the scavenging effect to DPPH radicals of flavonoids sample can got to 83.68%, when the concentration was 1.6mg/mL. When the concentration got to 6.4mg/mL, the scavenging effect to Hydroxyl radicals was 60.33%。...