红米米糠非淀粉多糖的提取纯化与结构表征

Extraction,purification,and structure characterization of non-starch polysaccharides from red rice bran

红米是我国产量最大的有色米,具有抗氧化、抗炎等功能,但其水溶性多糖资源并未被开发利用。该文以红米米糠为原料,脱脂后利用热水提取,经脱色、除蛋白、醇沉、透析制得红米米糠非淀粉多糖(non-starch polysaccharides from red rice bran,RRBP)。利用DEAE-52 Cellulose和Sephadex G-200分离纯化得到不同的部分,其中比例最大的为RRBP4组分。通过高效液相色谱、傅里叶红外光谱与完全酸水解、部分酸水解、β-消除、I 2-KI实验、刚果红实验等方法对RRBP4的分子质量、单糖组成、主链与侧链、糖苷键、分支程度与三螺旋构象进行分析。结果表明,RRBP4的相对分子质量为1.65×10^(5)Da,由甘露糖、核糖、鼠李糖、葡萄糖醛酸、半乳糖醛酸、葡萄糖、半乳糖、木糖和阿拉伯糖组成,其摩尔比例为0.29∶1.93∶0.35∶1.41∶0.50∶1.00∶5.58∶1.67∶2.56,是一种以半乳糖为主的酸性杂聚糖。RRBP4中有62.40%的多糖集中于侧链,是一种高度支化的多糖。RRBP4是以α-糖苷键为主且含有氨基酸的多糖,同时具有三螺旋结构。红米米糠非淀粉多糖的结构分析能够为开发其在食品工业中的应用提供科学基础数据。

Red rice is the largest yield of colored rice in China,with biological activities such as antioxidant and anti-inflammatory.But its water-soluble polysaccharide resources have not been exploited.Non-starch polysaccharides from red rice bran were prepared from red rice bran as raw material,by extracting with hot water,decoloring,deproteinizing,alcohol precipitation,and dialysis.Different fractions of extractive polysaccharides were isolated and purified using DEAE-52 Cellulose and Sephadex G-200,with the largest proportion being the RRBP4 component.Molecular weight,monosaccharide composition,main and side chains,glycosidic bonds,branching degree,and triple helix conformation of RRBP4 were identified by using HPLC,FT-IR,complete acid hydrolysis,partial acid hydrolysis,β-elimination,I 2-KI experiment,and Congo red test methods.Result showed that the relative molecular weight of RRBP4 was 1.65×10^(5) Da.RRBP4 was composed of mannose,ribose,rhamnose,galacturonic acid,glucuronic acid,glucose,galactose,xylose,and arabinose,the mole ratio of them was 0.29∶1.93∶0.35∶1.41∶0.50∶1.00∶5.58∶1.67∶2.56.RRBP4 was an acidic heteroglycan dominated by galactose.There were 62.40%polysaccharides located in the side chain,which was a highly branched polysaccharide.RRBP4 was a polysaccharide withα-glycosidic bonds and amino acids and had a triple helix structure.The structural analysis of water-soluble non-starch polysaccharides from red rice bran provided a scientific essential data for the development of their application in the food industry.