铁皮石斛多糖不同级分的制备、性质分析及免疫调节活性比较

目的:制备铁皮石斛多糖(DOP)的不同分级组分,比较其理化性质及体外免疫调节活性的差异,并对多糖结构特征与活性的关系进行初探。方法:采用分级醇沉的方法获得铁皮石斛多糖不同分级组分,并对各组分的糖、糖醛酸、蛋白质含量、单糖组成、分子量进行分析。以巨噬细胞RAW264.7为研究模型,比较DOP不同分级组分的体外免疫调节活性。结果:DOP和四个组分(F30、F40、F50和F50S)均为中性糖,各组分糖醛酸含量较DOP均有所降低,F50S蛋白质含量最高。DOP、F30、F40、F50和F50S的平均分子量分别为262.4、314.5、248.3、202.9和136.2 kDa。DOP、F30、F40、F50和F50S均主要由甘露糖和葡萄糖组成,其摩尔比分别为5.16:1、3.67:1、4.16:1、5.62:1和5.86:1。DOP和各分级组分均可显著(p<0.05)增强RAW264.7巨噬细胞的增殖能力、NO的释放以及TNF-α和IL-1β的分泌。结论:铁皮石斛多糖及其分级组分均有免疫调节活性,且分子量较小的免疫调节活性较强。

Preparation and Property Analysis of Polysaccharide Fractions from Dendrobium officinale and Comparison on Their in vitro Immunological Activity

Objective:To prepare and study the properties of polysaccharide fractions from Dendrobium officinale(DOP),compare their in vitro immunological activity and discuss the structure-bioactivity relationship. Methods:Precipitation with different ethanol was used to prepare the Dendrobium officinale polysaccharide fractions. The sugar,uronic acid,protein content,monosaccharide composition,and molecular weight of these fractions were analyzed. Their in vitro immunological activity were evaluated with macrophage RAW264.7. Results:The results indicated that DOP,F30,F40,F50 and F50S were all neutral sugars. The uronic acid contents of these fractions were lower than that of DOP,F50S had the highest protein content. The molecular weight of DOP,F30,F40,F50,and F50S were 262.4,314.5,248.3,202.9 and 136.2 kDa,respectively. DOP,F30,F40,F50,and F50S were mainly composed of mannose and glucose,with the ratio at 5.16∶1,3.67∶1,4.16∶1,5.62∶1 and 5.86∶1,respectively. DOP and its fractions could significantly(p<0.05)enhance the proliferation capacity of RAW264.7 macrophages,release of NO,and secretion of TNF-α and IL-1β. Conclusion:The polysaccharide fractions of Dendrobium officinale had the capacity of immune regulation,and the immunomodulatory activity of small molecular weight is stronger.