香菇柄多糖乙酰化修饰及其抗氧化活性

以香菇柄为原料，采用乙酸酐法制备乙酰化香菇柄多糖，考察不同乙酸酐用量在NaOH体系和甲酰胺体系中对多糖乙酰化修饰取代度以及多糖结构特性的影响，并对多糖及其乙酰化多糖的抗氧化活性进行评价。结果表明，在NaOH体系和甲酰胺体系中，香菇柄多糖乙酰化修饰取代度与乙酸酐用量均呈正相关，在乙酸酐用量为5 mL时，取代度分别为0.31和0.14。红外光谱表明，乙酰化修饰香菇柄多糖除具有多糖特征峰外，还出现了乙酰基的特征吸收峰，说明香菇柄多糖的乙酰化修饰成功。NaOH体系乙酰化修饰后多糖仍然具有三螺旋结构，而甲酰胺体系乙酰化修饰后多糖的三螺旋结构被破坏。抗氧化结果表明，香菇柄多糖乙酰化修饰前后均具有一定的抗氧化能力，并呈现一定的量效关系，且NaOH体系乙酰化多糖的抗氧化活性强于香菇柄多糖和甲酰胺体系乙酰化多糖，宜采用NaOH体系对香菇柄多糖进行乙酰化修饰。

Acetylation modification of Lentinus edodes stipe polysaccharide and its antioxidant activity

Using Lentinus edodes stipe as raw material,polysaccharide of L.edodes stipe was acetylated with acetic anhydride to yield acetylated polysaccharide.The effects of different acetic anhydride dosage on acetylated degree of substitution and structural characteristics of polysaccharide in NaOH system and formamide system were investigated,and the antioxidant activity of polysaccharide and acetylated polysaccharide were also evaluated.The results showed that the degree of substitution for acetylation modification of the polysaccharide was positively correlated with the amount of acetic anhydride in both NaOH system and formamide system.When the amount of acetic anhydride was 5 mL,the degrees of substitution were 0.31 and 0.14,respectively.The infrared spectrum results showed that the acetylated polysaccharide had not only the characteristic peak of polysaccharide,but also the characteristic absorption peak of acetylation group,which indicated that the acetylation modification of the polysaccharide was successful.After acetylation,the polysaccharide still had the triple helix structure in NaOH system,however,it was destroyed in formamide system.The antioxidant results showed that the polysaccharide had a certain antioxidant capacity no matter it was acetylated modification,which showed a certain dose-effect relationship as well.The antioxidant activity of acetylated polysaccharide in NaOH system was stronger than that in L.edodes stipe polysaccharide and formamide system.The results can be concluded that NaOH system was appropriate to acetylated modification for polysaccharide of L.edodes stipe.