谷物可溶性(1→3)(1→4)-β-D-葡聚糖结构与生理活性的研究进展

Research Progress in the Structure and Physiological Activity of Soluble (1→3)(1→4)-β-D-glucan from Cereal

摘要:

谷物β-葡聚糖是β-D-吡喃型葡萄糖基单元通过(1→4)-β-键重复连接并被单一(1→3)-β-D-键分离而形成的一种线性同聚多糖，同时也是谷物水溶性膳食纤维的主要成分，主要存在于大麦、燕麦、青稞、小麦和黑麦中。谷物可溶性β-葡聚糖的生理效应与其独特的结构具有密切关系，本文注重于谷物β-葡聚糖的分子结构特征与其在胃肠道中的生理活性的关系，总结了谷物可溶性β-葡聚糖在降低胆固醇、餐后血糖指数与胰岛素水平上等生理活性的研究，探讨了谷物β-葡聚糖对肠道菌群与免疫作用的新机制。对几种β-葡聚糖生理活性机理的研究进行了描述：增加小肠黏度水平因此延缓胃排空、消化和分子吸收，包括葡萄糖、膳食胆固醇和胆汁酸；于小肠中与胆汁酸相结合降低胆汁酸重吸收，进而促进利用胆固醇的胆汁酸合成；降低餐后血糖指数与胰岛素水平改善胰岛素敏感性；于盲肠、结肠中发酵改善肠道健康。

Abstract:

Cereal β-glucans are a type of linear homopolysaccharides formed by the linkage of β-D- glucopyranosyl units via (1→4)-β-linkage and separated by single (1→3)-β-linkages. They are the main component of water-soluble dietary fibers from cereals and are mainly found in barley, oat, hull-less barley, wheat, and rye. The physiological activity of soluble β-glucan from cereal is closely related to its unique structure of (1→3)(1→4)-β-D-glucan. This paper focused on the relationship between the characteristics of the molecular structure of cereal β-glucans and their physiological activity in the gastrointestinal tract. The physiological activities of cereal soluble β-glucans in reducing cholesterol, postprandial glycemic index, and insulin levels are summarized and new mechanisms underlying the effect of β-glucans on the intestinal flora and immune function are discussed. Studies on several mechanisms underlying the physiological activities of β-glucan are described. The viscosity level in the small intestine was increased, delaying the gastric emptying, digestion, and absorption of molecules, including glucose, dietary cholesterol, and bile acids. β-glucans bound with bile acid in the intestine to decrease the bile acid reabsorption, thus promoting the synthesis of bile acids from cholesterol. β-glucans improved insulin sensitivity by reducing postprandial glycemic index and insulin level and underwent colonic fermentation to improve intestinal health.