Study on the intestinal metabolism and absorption of polysaccharides from Dendrobium officinale

Dendrobium officinale polysaccharide (DOP) is widely recognized for its excellent pharmacological activities, however, the in-depth pharmacokinetic characteristic remains unrevealed, significantly hindering its further development. It was hypothesized that Bacteroides predominantly mediates the in vivo metabolism of DOP via polysaccharide utilization loci (PULs), and the resulting oligosaccharides can be directly absorbed by the intestine. To verify this hypothesis, metagenomic sequencing analysis was first employed, confirming that DOP stimulates an upregulation of PULs associated with carbohydrate metabolism within the gut microbiota dominated by Bacteroides. The metabolized oligosaccharides were correlated with highly expressed endo-β-1,4-mannanase from Bacteroides. Further utilizing fluorescent labeling techniques, it was demonstrated that oligosaccharides derived from DOP metabolism are directly absorbed by intestinal tissues. Unabsorbed metabolites subsequently undergo disordered metabolism by gut microbiota into small molecules such as short-chain fatty acids. Collectively, these findings provide novel evidence for elucidating the pharmacological activities of DOP and offer new insights into pharmacokinetic research for other polysaccharides.