Structural characteristics and biological activities of a pectic-polysaccharide from okra affected by ultrasound assisted metal-free Fenton reaction
Structural characteristics and biological activities of a pectic-polysaccharide from okra affected by ultrasound assisted metal-free Fenton reaction
复制标题
超声辅助无金属芬顿反应影响秋葵果胶多糖的结构特征和生物活性
DOI：
10.1016/j.foodhyd.2021.107085
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发表时间：
2021-08-05
影响因子：
10.7
通讯作者：
Zou, Liang
中科院分区：
文献类型：
--
作者：
Wu, Ding-Tao;He, Yuan;Zou, Liang
研究超声辅助无金属芬顿（H2 O2-抗坏血酸体系）反应对黄秋葵果胶多糖结构和生物学特性的影响。采用超声辅助芬顿处理玉米秸秆0.5、1.0和3.0 h，成功制备了三种降解组分（DOPP-1、DOPP-2和DOPP-3）。测得D 0 PP、D 0 PP-1、D 0 PP-2和D 0 PP-3的分子量分别为2.84 X 10（5）、1.90 X 10（5）、8.27 X 10（4）和4.65 X 10（4）Da。超声波辅助芬顿处理能显著降低OPP的表观粘度、回转半径和支化度，但其酯化度显著增加，表明游离糖醛酸比酯化糖醛酸更容易受到H2 O2-抗坏血酸体系产生的羟基自由基的影响。超声辅助芬顿处理对OPP的主链和链构象没有明显影响，适当的超声辅助芬顿处理能显著提高OPP的抗氧化、降血糖和免疫调节活性，且OPP的抗氧化和降血糖活性与其分子量和酯化度有关，其免疫调节活性与其支化度、分子量及酯化度密切相关。结果表明，超声辅助无金属芬顿反应在黄秋葵果胶多糖的降解和改性以提高其生物活性方面具有潜在的应用价值。此外，黄秋葵果胶多糖的降解产物具有开发抗氧化、降血糖和免疫调节功能食品的潜在应用价值。
This study aimed to investigate the impact of ultrasound assisted metal-free Fenton (H2O2-ascorbic acid system) reaction on structural and biological properties of a pectic-polysaccharide extracted from okra (OPP). Three degraded fractions (DOPP-1, DOPP-2, and DOPP-3) were successfully prepared by ultrasound assisted Fenton treatment of OPP for 0.5, 1.0, and 3.0 h, respectively. Molecular weights of OPP, DOPP-1, DOPP-2, and DOPP-3 were determined to be 2.84 x 10(5), 1.90 x 10(5), 8.27 x 10(4), and 4.65 x 10(4) Da, respectively. Besides, the ultrasound assisted Fenton treatment could obviously reduce the apparent viscosity, radius of gyration, and branching degree of OPP. However, its degree of esterification notably increased, suggesting that free uronic acid was more susceptible to hydroxyl radicals generated by H2O2-ascorbic acid system than that of esterified uronic acid. Furthermore, the ultrasound assisted Fenton treatment made no significant changes on the backbone and chain conformation of OPP. Moreover, an appropriate ultrasound assisted Fenton treatment can remarkably promote the antioxidant, hypoglycemic, and immunomodulatory activities of OPP. Indeed, the antioxidant and hypoglycemic activities of OPP were associated with its molecular weight and degree of esterification, and its immunomodulatory activity was closely correlated to its degree of branching and molecular weight, as well as degree of esterification. Results suggest that the ultrasound assisted metal-free Fenton reaction has potential applications in degradation and modification of okra pectic-polysaccharides to improve their biological activities. Furthermore, the degraded products derived from okra pectic-polysaccharides have potential application for the development of functional foods with antioxidant, hypoglycemic, and immunomodulatory activities.