Supplementary file 1_Polysaccharides from Er Chen Decoction: gastrointestinal fate, gut microbiota modulation and metabolomics.docx

During simulated digestion, the total sugar and reducing sugar contents, molecular weight distribution, monosaccharide composition, and infrared spectral profiles of PECD showed no significant changes, suggesting that its major polysaccharides were largely resistant to upper gastrointestinal digestion. During in vitro fecal fermentation, PECD was progressively utilized by the gut microbiota, accompanied by a reduction in pH and an increase in SCFAs concentrations.

PECD supplementation was also associated with shifts in microbial community composition by enriching genera such as Bifidobacterium and Mitsuokella, while depleting others including Klebsiella and Bilophila. Untargeted metabolomic analysis revealed alterations in metabolites related to phenylalanine metabolism, caffeine metabolism, and arginine biosynthesis, suggesting their potential involvement in microbial response to PECD.</p>Conclusion<p>PECD exhibited limited absorption, resistance to upper gastrointestinal digestion, susceptibility to fecal microbial fermentation, which altered microbial composition, SCFAs, and metabolic profiles, supporting its further study as a candidate bioactive polysaccharide.</p>