Intestinal metabolic characteristics of Smilax china L. pectic polysaccharide and prediction of its gut microbiota-mediated mechanism

SCLP remained intact in the stomach and small intestine after oral administration. • SCLP was degraded into oligosaccharide fragments in the cecum and colon. • The intestinal metabolism of SCLP was gut microbiota-dependent. • Phocaeicola vulgatus and Bacteroides uniformis were involved in SCLP metabolism. This study aimed to investigate the intestinal metabolic characteristics and mechanisms of the pectic polysaccharide isolated from the medicinal plant Smilax china L. (SCLP). Firstly, in vitro simulated digestion confirmed that SCLP remained stable in simulated digestive fluids. Subsequently, in vivo real-time tracking of intestinal metabolism based on fluorescent labeling revealed that SCLP maintained its prototype in the small intestine and began to be degraded into fragments (Mw < 4000 Da) upon reaching the cecum and colon, where it was retained for prolonged periods. Pseudo-sterile mouse experiments indicated the mediating role of gut microbiota in SCLP metabolism. Furthermore, metagenomic sequencing suggested that SCLP increased the proportion of polysaccharide utilization loci (PULs) from Phocaeicola vulgatus and Bacteroides uniformis , elevated the gene numbers of carbohydrate-active enzymes (CAZymes) including GHs, GTs and CBMs, and activated pathways of carbohydrate metabolism. Finally, in vitro bacterial culture study verified the degradation and utilization of SCLP by Phocaeicola vulgatus and Bacteroides uniformis . In summary, this work elucidates the intestinal metabolic profile of SCLP, providing valuable insights for its further development and utilization.