| Modern landscape architecture bases on the ornamental recreation, pays more attention to its ecological function and plays an important role in improving surrounding environment. Except for the recreation, ornamental and ecological function, garden is good to public health. As the basis of the health garden, it is a fashion to introduce medicinal garden plants which have health care functions in modern gardens, and medicinal garden plants have been becoming more and more popular. Therefore, it is a new trend in landscape design that introducing medicinal garden plants into landscape space. This study is based on these and we focus on one of the medicinal garden plant-Dendrobium devonianum Paxt, aim to make it in full guarantee under the premise of landscape ecological function and beautification, further develop its health care function to provide theoretical guidance and scientific basis.This experiment first Dendrobium devonianum polysaccharide enzymes formulation of process optimization, first used single factor experiment to determine the effect on the extraction yield the highest three factors for the amount of enzyme concentration, digestion temperature and pH. And then through the BBD response surface experiment to optimize the extraction process and the optimized:the best conditions were enzyme concentration 0.94%, enzymolysis temperature 51.06℃, pH=4.94. In this condition, the predictional polysaccharide extraction yield of of Dendrobium devonianum was 157.93 mg/g. After three validation experiments, measured the average extraction yield was 157.58 mg/g, which was consistent with previous resultThen, according to the method of extraction process of Dendrobium devonianum polysaccharide was extracted. Extracted protein by sevage reagent, tested the ultraviolet absorption peak at 280 nm determine protein content in the solution. After that, the polysaccharide extract alcohol sink to remove pigment repeatedly, until the extract color close to colorless, in ethanol concentration 40%,60% and 40% respectively under the alcohol settling out three different molecular weight of polysaccharides, and named 40%,60% and 80% polysaccharide. Washed these three kinds of polysaccharides in acetone and ethyl acetate to remove organic impurities, dissolved again, put them in the dialysis bag dialysis small molecules to remove impurities. Finally after drying dialysis polysaccharide solution decompression, got the solid polysaccharide.The acidic polysaccharide content determination showed that acidic polysaccharides content is very low when this method was used to extract the total polysaccharides, this directly led to the weak polysaccharide antioxidant capacity in the subsequent antioxidant activity experiment, the uronic acid contents of 40%,60% and 80% polysaccharide were 3.05%,2.96% and 2.98% respectively, the sulfate content was 00.7% and 0, respectively. In the study of antioxidant activity, these three polysaccharides almost do not have a reducibility, the clearance capacity of three kinds of polysaccharides on DPPH free radical was negligible. As for the removal of the super oxygen free radicals, these three polysaccharides had a very weak ability, the clearance were 5.63%,9.22% and 5.63% respectively in the concentration of 2.56 mg/mL.80% polysaccharide had a certain ability in clearing ABTS free radicals, reaching 14.86% in the concentration of 2.56 mg/mL,, while the other two kinds of polysaccharides were 0.03% and 0.54%, respectively. To hydroxyl free radicals,40% polysaccharide showed a strong ability of clear, reaching 27.54% in the concentration of 2.56 mg/mL, which was far higher than that of the other two polysaccharides(0.70% and 0, respectively). |
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