Isolation And Preliminary Structure Analysis Of Polysaccharides From Chinese Yam

Chinese Yam, also named Rhizoma Dioscoreae Oppositae, has been used as healthy food and herbal ingredients in traditional Chinese medicine. Polysaccharide extraction of Chinese yam was counted as the main active material, it can reduce blood glucose in diabetic mice, and at the same time, it can inhibitα-amylase activity.This paper used fresh yam as research object, after finding out the constituent which has the effect of hypoglycemic, the constituent was isolated, purified and the structure analysis was done then. This was important for opening out relationship between structure and full use of Chinese yam resource.The process of polysaccharide extraction of Chinese yam was studied, too. With the single factor experiment and orthogonal experiment, the optimal extracting conditions are as follows: the extracting temperature is 70℃, the extracting time is 90min, the adding ratio of water is 1∶6, And the extraction ratio was 0.20%.The polysaccharide was divided into three parts: MY,YP₁,YP₂, Animal experiment find that MY can lower blood glucose level of diabetic mice effectively. The inhibition of their activity onα-amylase was studied, too. The experimental results show that: MY can inhibitα-amylase activity effectively, YP₁ can inhibit to a certain extent while YP₂ has no inhibition activity.MY was purified and identified by Sephacryl S-400,then we got two pure matters, named as MYP₁,MYP₂. The carbohydrate moiety of MYP₁ contained arabinose, glucose, galactose at a mass ratio of 1:20.7:3.3. It also has protein in it, which was rich in leu, glu, arg, asp. With the method of NMR, we find the probable chemical construction of MYP₁ was that: Glucose link with glycosidic bond ofβ-1→2 andβ-1→4, galactose and arabinose was gap juncted or forming lateral chain with them byβ-1→2 orα-1→2 bond. The carbohydrate moiety of MYP₂ is the same as MYP₁, but the mass ratio of MYP₂ is 1:20.7:3.3. The amino acid component of MYP₂ consists of asp, glu, val, arg, lys. The detailed structure of MYP₂ is very complex, which need to research deeply.