马勃状硬皮马勃胞外多糖的分子结构及抗氧化活性研究

THE MOLECULAR STRUCTURE AND ANTIOXIDANT ACTIVITY OF POLYSACCHARIDES FROM SCLERODERMA AREOLATUM EHRENB

对发酵罐制得的马勃状硬皮马勃胞外多糖(EPS)进行分离纯化,并表征了其结构,测定了抗氧化活性.结果表明,马勃状硬皮马勃EPS分离纯化得到两个组分Fr-I和Fr-II,其相对分子质量分别为627 500和4 820;红外光谱分析发现两组分均为α-吡喃型甘露糖苷酸性杂多糖;气相/质谱(GC/MS)测定表明,两组分所含单糖为鼠李糖、核糖、木糖、葡萄糖醛酸、半乳糖、葡萄糖、甘露糖和半乳糖醛酸;SEC/MALLS测定表明,两种EPS分散性很低,在水溶液中以球形构象存在,是一种高度紧密的杆状多糖聚集体;抗氧化测定表明,EPS质量浓度为10 mg/m L时,对·OH自由基的清除率为22.65%;质量浓度为5 mg/m L时,对·DPPH自由基的清除率高达41.32%,表现出良好的抗氧化活性.本研究为马勃状硬皮马勃EPS构效关系研究及其在医药行业的应用奠定了基础.

Fungus polysaccharide has multiple physiological functions,such as reducing blood fat and blood sugar,anti-tumor activity,anti-radiation,anti-aging,hepatoprotective and antioxidant,which make it becomethe focus of research and development in pharmaceutical and health products industry in domestic and foreign.The present study was to investigate the structure and the antioxidant activity of the extracellular polysaccharide（EPS）,which was isolated and purified from the fermentation of Scleroderma areolatum Ehrenb. The results showed that after the EPS was isolated,two fractions（Fr-I and Fr-II） were obtained,the relative molecular weights of which were 627 500 and 4 820 respectively. FTIR analysis showed that both fractions wereα-configuration of mannopyranoside acidic polysaccharides; the results of gas chromatography/mass spectrometry（GC/MS）showed that the monosaccharide components of EPS contained rhamnose,ribose,xylose,glucuronic acid,galactose,glucose,mannose and galactose. The monosaccharide components of the two fractions were the same,but the contents were different. The two fractions both contained glucuronic acid and galacturonic acid,suggesting that the EPS from fermentation may be acidic polysaccharide and the results were consistent with the infrared spectrum analysis. The content of mannose was higher than other monosaccharides,which was consistent with the characteristics absorption peaks at 810 cm-1in the infrared spectra. SEC/MALLS results showed that the dispersion of two EPS fraction was very low,and EPS kept a rigid rod conformation in aqueous solution. The EPS was a highly compact aggregate with branches. The viscosity,molecular weight and square radius of Fr-II were smaller than Fr-I,especially the square radius,which meant that the chain of Fr-II was folded and the structure was compact. The antioxidant determination showed that OH scavenging rate was 22.65% when EPS concentration was 10 mg/m L,while the DPPH scavenging rate was 41.32% when the EPS concentration was 5mg/m L,all of which suggested that the EPS had good antioxidant activity. It was conclude that the present study laid a foundation for the research on the structure-activity relationship of the EPS and its application on the pharmaceutical industry.