Study On Extraction, Isolation, Purification, Structure And Antioxidant Activity Of Polysaccharide From Asparagus

Polysaccharides, Flavonoids, Saponins are the main natural active ingredients in Asparagus offocinalis.The extraction of active ingredients from asparagus is one important aspect of further processing development.This could not only increase the value, but also make full use of the waste from processing and reduce the pollution of the environment.The extraction and purification technology of polysaccharides from asparagus, and the basic structure and antioxidant activity were studied in this article.The result were as follows:1. The quantity contained of fats, proteins, polysaccharides and some human essential elements were determined,and made a simple analysis.This research provide theoretical basis for the further study and development of asparagus as a natural plant resources in China.Besides, it enriches the theory of food chemistry and food nutrition.2. The waste of asparagus were dried by air, then crushed with 40 mesh to obtain the powder.The extraction technology of polysaccharides from green asparagus using hot water was studied.The effects of the parameters of extraction temperature, extraction time, ratio of raw material to water, extraction times were optimized by using statistical techniques such as a four factor, three level Box-Behnken factorial design(BBD) and RSM.Base on the RSM analysis, optimum condition were:extraction temperature 81.10℃, extraction time 2.02h, ratio of raw material to water 1:25, extraction times three times.The model was listed as follows Y=-77.324+1.575A+14.545B+5.983×10-2C+ 6.922D-9.710×10-3A2-3.604B2-1.201D2.Under the optimized conditions the extraction of crude polysaccharides was 12.67%, the experimental values were in close agreement with values predicted by the model.The result analyzed by ANOVA show that the influence to the yield of polysaccharide indicated extraction times> ratio of raw material to water> extraction temperature> extraction time.3. The research aimed to seek the suitable deproteinization methods from asparagus polysaccharides.The different ways to removing protein from polysaccharide among Sevag, HCl, TCA and TPS is compared.The result shows TPS method is the best way to removing protein. At the basis of single-factor experiment, the suitable range of trypsin volume, hydrolytic temperature, hydrolytic time were determined.The effects of the parameters of trypsin volume, hydrolytic temperature, hydrolytic time were optimized by using statistical techniques such as a three factor, three level Box-Behnken factorial design(BBD) and RSM.The result show that:when the main indicator was retention rate of polysaccharides, the model was listed as follows:Y1=4.912+13.767A-0.489B+2.654 C-1.446A2-0.0303C2, the main indicator was removal rate of protein, the model was listed as follows:Y2=-48.046+16.020A+3.864B+0.601C-1.568A2-0.0568B2.Both of them were considered, optimum condition were:trypsin volume 4.87%, hydrolytic temperature 36.03℃, hydrolytic time 48.26min.Under the optimized conditions the retention rate of polysaccharides and removal rate of protein were 87.94% and 87.75% respectively.After removing protein, A1 and A2 were achieved by isolation and purification with DEAE-SephadexA-25 cellulose.APS-1,APS-2 were achieved by further purified with Sephadex G-200 gel column, and the molecular were measured by Sephadex G-200 gel filtration for 8.47×104,13.8×104.4. The infrared spectra of APS-1, APS-2 show the typical characteristic absorption peak of polysaccharides.GC analysis show that APS-1, APS-2 were at least composed by rhamnose, arabinose, xylose, glucose, galactose.The content were 12.76%,20.65%, 7.03%,19.81%,39.75% and 15.26%,18.85%,5.84%,14.62%,45.43% respectively. In vitro, it was shown that the polysaccharides were found to have capacity of scavenging free radicals.According to the value of IC50, the scavenging ability of Vc was higher than Asparagus polysaccharide on hydroxyl free radical, superoxide anion free radical and DPPH free radical. The multiples were 27.1,27.4,169.1 respectively. But Asparagus polysaccharide still has a scavenging effect.