The gastrointestinal absorption characteristics and metabolic mechanisms of polysaccharides from Hohenbuehelia serotina.

In order to elucidate the digestion, absorption and metabolism mechanism, Hohenbuehelia serotina polysaccharides were successfully labelled by fluorescein isothiocyanate (FITC-Tyr-HSP), with the fluorescent substitution degree of 0.37 %. FITC-Tyr-HSP with excellent physiological stability possessed the significant fluorescent characteristics, which could be dynamically monitored by in vivo fluorescence imaging and high performance gel permeation chromatography-fluorescence detector (HPGPC-FLD). Through investigation of gastrointestinal digestion in vitro, the degradation of HSP was only occurred in small intestinal fluid. The results of in vivo studies also confirmed that a small amount of HSP were degraded in small intestine, and then absorbed by intestinal epithelial cells to enter into the bloodstream, reaching to liver, spleen and kidney. Meanwhile, most of HSP that could not be digested were directly transported to cecum and colon, where they were metabolized by gut microbiota to produce SCFAs, with the total content of which reached to 60.52 mmol/L after gavage for 24 h. Ultimately, the polysaccharides were excreted from the body mainly by feces and urine pathways. This study is meaningful for providing a practical basis to elucidate the digestion, absorption and metabolism of polysaccharides.