In vitro digestion and fecal fermentation behaviors of exopolysaccharide from Morchella esculenta and its impacts on hypoglycemic activity via PI3K/Akt signaling and gut microbiota modulation

Abstract

This study aimed to evaluate the effects of gastrointestinal digestion on the physicochemical properties and hypoglycemic activity of extracellular polysaccharides from Morchella esculenta (MEPS). The results showed that the MEPS digestibility was 22.57 % after saliva-gastrointestinal digestion and only partial degradation had occurred. Contrarily, after 48 h of fecal fermentation, its molecular weight and molar ratios of the monosaccharide composition varied significantly due to being utilized by human gut microbiota, and the final fermentation rate was 76.89 %. Furthermore, the MEPS-I, the final product of saliva-gastrointestinal digestion still retained significant hypoglycemic activity, it alleviated insulin resistance and increased the IR cells glucose consumption by activating PI3K/AKT signaling pathway. MEPS-I treatment reduced the proportion of Firmicutes to Bacteroidetes, and the relative abundance of beneficial bacteria that enhanced insulin sensitivity and glucose uptake was promoted. This research can provide a theoretical basis for the further development of Morchella esculenta as a health functional food.