鲜山药切片,按1∶6的料液比(g∶mL)加入去离子水,于70℃提取,浓缩后经体积分数80%的乙醇沉淀,沉淀物经DEAE-纤维素柱层析分离后得到3个组分MY、YP1、YP2,其中MY对α-淀粉酶有抑制作用。MY多次经过SephacrylS-400凝胶柱层析后得到一个有对称峰的洗脱曲线,记为MYP。其单糖组成为阿拉伯糖、葡萄糖、半乳糖,其质量比为1∶20.7∶3.3;主要氨基酸组成为亮氨酸、谷氨酸、精氨酸、天门冬氨酸。其可能的化学结构为葡萄糖以β-1→2和β-1→4糖苷键相连,半乳糖与阿拉伯糖以β-1→2或α-1→2键与其间隙相连或形成侧链。

Polysaccharides,named MY,YP1,YP2 respectively,was isolated from fresh Chinese yam with water(70℃,Solid-liquid ratio=1∶6),alcohol sedimentation(80%,v/v),DEAE-52 column.The inhibition of their activity on α-amylase was studied.The results show that MY inhibits α-amylase activity to a certain extent.MY was purified and identified by Sephacryl S-400 named as MYP.The carbohydrate moiety contained arabinose,glucose,galactose at a mass ratio of 1∶20.7∶3.3.It was also rich in protein,such as leu,glu,arg,asp.With the method of NMR,we found the probable chemical construction of MYP was:glucose link with glycosidic bond atβ-1→2 and β-1→4,galactose and arabinose was linked at the gap or lateral chain by β-1→2 or α-1→2.