Abstract：
Aureobasidium pullulans β-(1 → 3, 1 → 6)-glucan (APG) has a high degree of β-(1 → 6)-glucosyl branching and a regular triple helical structure similar to that of schizophyllan. In this study, APG was carboxymethylated to different degrees of substitution (DS = 0.51, 1.0, and 2.0, denoted CMAPG 1-3, respectively) using a heterogeneous reaction. With increasing DS, the triple-helix structure drastically decreased and converted to a random coil structure in CMAPG 3. Further, aqueous solutions of CMAPG changed from pseudoplastic fluids to perfect Newtonian liquids with increasing DS, indicating that the intra- and intermolecular hydrogen bonds had been cleaved by the substituents to form a random coil structure. In addition, APG and CMAPG solutions exhibited scavenging ability against hydroxyl, organic, and sulfate radicals. It was also found that the carboxymethylation of APG drastically enhanced the organic radical scavenging ability. On the basis of the relationship between the DS and radical scavenging ability of the CMAPG samples, we believe hydroxyl and organic radicals were preferably scavenged by the donation of hydrogen atoms from the glucose rings and the methylene moieties of the carboxymethyl groups, respectively. Considering the obtained results, CMAPG and APG are expected to have applications in pharmaceuticals, functional foods, and cosmetics as antioxidant polysaccharides.
摘要：
普鲁兰梭菌β-（1→3，1→6）-葡聚糖（APG）具有高度的β-（1→6）-葡萄糖基分支，并且具有与裂竹多糖相似的规则三螺旋结构。在这项研究中,使用非均相反应将APG羧甲基化至不同的取代度(DS=0.51、1.0和2.0,分别表示为CMAPG1-3)。随着DS的增加,CMAPG3中的三螺旋结构急剧减少并转化为无规卷曲结构。Further,随着DS的增加，CMAPG的水溶液从假塑性流体变为完美的牛顿液体，表明分子内和分子间氢键已被取代基裂解形成无规卷曲结构。此外,APG和CMAPG溶液表现出对羟基的清除能力，有机,和硫酸根。还发现APG的羧甲基化大大增强了有机自由基的清除能力。根据CMAPG样品的DS与自由基清除能力之间的关系，我们认为羟基和有机自由基优选通过从葡萄糖环和羧甲基基团的亚甲基部分中提供氢原子来清除，分别。考虑到所获得的结果，CMAPG和APG有望在制药领域应用，功能性食品,和化妆品作为抗氧化多糖。
