基于膜技术的桑葚多糖分级分离及生物活性组分筛选

采用了膜技术分级分离桑葚多糖（Mori fructus polysaccharide，MFP），并探究了不同分子量桑葚多糖的抗氧化、降血糖、抗过敏和体外乙醇脱氢酶活性。以桑葚为原料，通过热水浸提后采用300、50、5和1 kDa超滤膜对桑葚多糖进行分级分离，分别记为MFP300、MFP50、MFP5和MFP1。比较4种孔径的超滤膜分离的桑葚多糖组分主要成分、抗氧化活性、降血糖活性、抗过敏活性和体外乙醇脱氢酶活性的差异。结果表明，4种多糖的主要成分和生物活性表现出一定的差异。MFP1、MFP5、MFP50和MFP300的总糖含量分别为46.34%、68.45%、48.60%和66.32%，糖醛酸含量分别为3.34%、22.78%、16.11%和21.48%，还原糖含量分别为16.51%、6.03%、7.90%和6.67%。生物活性筛选表明，MFP300清除DPPH自由基和ABTS+自由基的IC₅₀值分别为0.2235和0.2979 mg·mL?1，抑制透明质酸酶能力的IC₅₀值为0.6634 mg·mL?1，激活体外乙醇脱氢酶能力的IC₅₀值为10.2646 mg·mL?1，表现出最好的抗氧化、抗过敏和体外乙醇脱氢酶活性。MFP1抑制α-葡萄糖苷酶和α-淀粉酶能力的IC₅₀值分别为0.7944和4.6419 mg·mL?1，表现出最好的降血糖活性。综上所述，经膜技术分级分离得到的不同分子量范围的桑葚多糖在主要成分和生物活性方面有一定差异，为桑葚多糖分级技术的改进升级和桑葚多糖“构-效”关系研究提供理论基础。

Separation of Mori fructus Polysaccharides and Screening of Bioactive Fractions Based on Membrane Technology

Membrane technology was used for the graded separation of Mori fructus polysaccharides, and its antioxidant, hypoglycemic, anti-allergic and in vitro alcohol dehydrogenase activities were studied. The Mori fructus polysaccharides were carried out by hot water extraction using ultrafiltration membranes with pore sizes of 300, 50, 5 and 1 kDa, respectively, as MFP300, MFP50, MFP5 and MFP1. The differences in the main components, antioxidant activity, hypoglycemic activity, antiallergic activity and in vitro ethanol dehydrogenase activity of Mori fructus polysaccharide fractions separated by ultrafiltration membranes of four pore sizes were compared. The results showed that the major components and biological activities of the four polysaccharides showed some differences. The total sugar content of MFP1, MFP5, MFP50 and MFP300 were 46.34%, 68.45%, 48.60% and 66.32%, respectively, while the glyoxylate content were 3.34%, 22.78%, 16.11% and 21.48%, respectively, and the reducing sugar content were 16.51%, 6.03%, 7.90% and 6.67%, respectively. Bioactivity screening showed that MFP300 scavenged DPPH radicals and ABTS+ radicals with IC₅₀ values of 0.2235 and 0.2979 mg·mL?1, respectively, inhibited hyaluronidase with IC₅₀ values of 0.6634 mg·mL?1, and activated in vitro ethanol dehydrogenase with IC₅₀ values of 10.2646 mg·mL?1. MFP300 was exhibited the best antioxidant, anti-allergic and in vitro ethanol dehydrogenase activities compared with the other three components. Compared with the other three components, MFP1 exhibited the best hypoglycemic activity with IC₅₀ values of 0.7944 and 4.6419 mg·mL?1 for its ability to inhibit α-glucosidase and α-amylase, respectively. In conclusion, there were some differences in the main components and biological activities of Mori fructus polysaccharides obtained by membrane classification and separation, which could provide a theoretical basis for the improvement and upgrading of Mori fructus polysaccharide classification technology and the study of the 'structure-effect' relationship of Mori fructus polysaccharides.