V-type starch-galloyl-based polyphenol complex stimulates GLP-1 and PYY secretion and improves satiety in mice

Galloyl-based polyphenols including gallic acid (GA) and tannic acid (TA) were used to form complexes with high-amylose maize starch (HAMS). The relationship among complex structure, starch digestibility in vitro, and postprandial glycemic response, hormone concentration and satiety in mice were investigated. Both GA and TA interacted with starch through noncovalent bonds and formed complexes with V-type crystalline structure. The polyphenol loading content in HAMS-TA was higher than HAMS-GA, probably because TA has more galloyl moieties. In vitro digestion revealed HAMS-TA/GA complexes had lower digestion rate (k) and proportion of digestible starch (C_∞) than control samples, attributing to their higher crystallinity and inhibition on α-amylase. HAMS-TA had lower k and C_∞ than HAMS-GA, resulted from its higher polyphenol loading content. In vivo digestion in mice indicated complexes had lower glycemic response, higher concentrations of GLP-1 and PYY than control groups. They also showed good ability in decreasing glycemic elevation after a subsequent meal and enhancing satiety. HAMS-TA exhibited better performance than HAMS-GA. The in vitro and in vivo results are in good agreements, suggesting the potential ability of starch-galloyl-based polyphenol complexes, especially HAMS-TA complex, in preventing type-2 diabetes and obesity. These would provide guidance for developing starchy foods with functional properties.