The interaction between mulberry leaf polyphenols and polysaccharides during digestion and colon fermentation

The digestion and absorption characteristics of mulberry leaf polyphenols (MLPP), polysaccharides (MLPS), and polyphenol-polysaccharide complex (PPPS) were compared and the changes in short chain fatty acids (SCFAs) were analyzed during the fermentation process. The impact of PPPS on the structural composition of intestinal microbiota was investigated based on 16S rDNA gene sequencing. The digestibility rates of polyphenols in MLPP and PPPS were 59.48% and 79.95%, respectively, while no free monosaccharide were detected in MLPS and PPPS, indicating that polysaccharides promoted the digestion of polyphenols in PPPS, while the existence of polyphenols had no effect on the digestion of polysaccharides in terms of the monosaccharide release. The production of intestinal microbiota SCFAs in PPPS group was significantly higher in the amounts of acetic acid, propionic acid, valeric acid and butyric acid during the 0–12 h fermentation process accompanied with sharp decrease in pH value, while more isobutytic acid and isovaleric acid were produced in MLPS group at the 12–24 h fermentation stage. PPPS increased the relative abundance of Fusobacteriun, while decreased the relative abundance of Collinsella aerofaciens, Romboutsia ilealis, and Lachnospiraceae in gut microbiota significantly, which might contribute to the synergistic effect of polyphenol and polysaccharide in regulating lipid metabolism.