The Study On The Extraction,Purification And Vitro Antioxidant Activity Of The Iron Yam Polysaccharide

Chinese Yam is one plant of the Dioscorea opposita Thunb.Its planting area inChina distributed in the North China, Northwest China and the Yangtze River Basin of Jiangxi, Hunan and other regions.The yam polysaccharide was the typical of bioactive substances.lt has became a trend to research on how to improve the extraction rate of polysaccharides,purification technology explorationand the monosaccharide composition of polysaccharides.It is helpful to promote the development of the yam planting and processing industry in our province.Meanwhile,promote the deep processing and active substance extracted of the yam.This paper compared the differences of nutritional components in three types of Chinese Yam,explored the extraction process of polysaccharides from Chinese Yam, the purification and identification of polysaccharide and the antioxidant effects of polysaccharides in vitro.The results were as follows:The basic nutritional differences between normal Chinese yam.Dioscorea opposita Thunb and Iron Dioscorea were notable.Results showed that moisture content of the normal Chinese yam is higher than the other two pieces is 86.46%.The total ash content of three species of yam were the same.is about 2.5%.The crude fat content were low,the protein content of Iron Dioscorea is slightly higher than the others,is9.57%.The Iron Dioscorea has the lowest content of the reducing sugar and the highest content of the polysaccharides and the starch.The results were 0.08%,8.26%.and 26%.The highest content of saponins and allantoin is also the Iron Dioscorea,the results were 0.74%and 1.0%.This paper choosed the method of water extraction and alcohol precipitation to extract the yam polysaccharides. Select the four indexs of extract liquid ratio, extraction temperature, extraction timeand extraction pH,used the method of response surface to optimize the extraction process of Polysaccharide from Chinese yam.The optimized processing parameters were determined.including solid-liquid ratio of 9,extraction temperature of 71℃,extraction time of 2.3h and extract pH of 7.16.The theoretical yield of the yam polysaccharide is 9.57%.The yam polysaccharide extraction was purified by macroporous resin and got a neutral polysaccharides and acidic polysaccharides The eluting agent was distilled water and 0.01MNaCl.The elution rate was 2mL/min.Neutral polysaccharides was further purified by SephadexG-100.The eluting agent was 0.01MNaCl.The elution rate was 2mL/min.It got a higher content of Single eluting peak and has a better separation effect.The purified neutral polysaccharides was by acetylation and gas chromatography The carbothydrate moiety of it contained mannose,glucose and galactose, the mass ratio of them was 4.22:12.82:1The purified Chinese yam polysaccharide was used in vitro tests,respectively through its scavenging effect on DPPH, hydroxyl radical, superoxide anion and comparied with the normal antioxidant VE.The results show that,Chinese yam polysaccharide has the strong in vitro antioxidant activity.The clearance rate of DPPH, hydroxyl radical and superoxide anion were the highest when the mass concentration was 300ug/mL.The results were respectively 81%、88% and 68%.The antioxidative activity was higher than antioxidant VE.