黑木耳多糖的磷酸化修饰、结构表征及体外降糖活性

Structural Characterization and Hypoglycemic Effect in Vitro of Phosphorylated Auricularia auriculata Polysaccharide

利用加压剪切联合萃取技术提取的黑木耳多糖为原料,以三偏磷酸钠为交联剂,不同温度下进行磷酸化修饰,并对其进行结构表征及体外降血糖活性研究。结果表明:磷酸化黑木耳多糖主要由木糖、果糖、甘露糖以及葡萄糖组成的杂多糖,随着温度的升高磷酸化黑木耳多糖相对分子质量明显下降,并出现三股螺旋结构。红外图谱显示在1205、898 cm^(-1)处出现了P=O及P-O-C的特征吸收峰。核磁共振光谱分析表明磷酸化修饰主要发生在C6位的羟基上,且在δ0~1.5范围内出现了磷酸基团中P的信号峰。扫描电镜结果表明修饰后黑木耳多糖表面形貌变化明显,相比修饰前多糖更加细小、破碎。且对α-葡萄糖苷酶和α-淀粉酶具有较强的抑制作用,当PAAP-4质量浓度为5.0 mg/mL时,α-葡萄糖苷酶抑制率为56.89%,体外降血糖活性增强。

In this study,the Auricularia auriculata polysaccharides extracted using high pressure-shearing extraction method were phosphorylated at different temperatures using sodium trimetaphosphite as a crosslinking agent,and the structure and in vitro hypoglycemic activity of the modified polysaccharides were characterized.The results showed that the phosphorylated polysaccharides were heteropolysaccharides mainly composed of xylose,fructose,mannose and glucose.With the increase of temperature,the molecular mass of the phosphorylated polysaccharides decreased significantly and a triple-stranded helical structure was observed.Infrared(IR)spectra showed that the characteristic absorption peaks of P=O and P–O–C appeared at 1205 and 898 cm^(-1).Nuclear magnetic resonance(NMR)spectra showed that the phosphorylation mainly occurred on the C6 hydroxyl groups,and the signal peak of P in the phosphate group appeared in the range ofδ0–1.5.Scanning electron microscopic(SEM)results showed that the surface morphology of the modified polysaccharides changed significantly,and it was finer and more broken compared to the original polysaccharides.In addition,5.0 mg/mL of the phosphorylated polysaccharide PAAP-4 had strong inhibitory effect onα-glucosidase andα-amylase.The inhibitory rate ofα-glucosidase was 56.89%,and the in vitro hypoglycemic activity was enhanced compared to that of the original polysaccharides.