Structural characterization of a neutral heteropolysaccharide from Pholidota chinensis Lindl. and its protective effects against intestinal inflammation via barrier enhancement and gut microbiota modulation

The polysaccharides extracted from Pholidota chinensis Lindl. was first identified as P. chinensis Lindl. polysaccharide (PCLP). PCLP was characterized by monosaccharide analysis, molecular weight determination, nuclear magnetic resonance (NMR) spectroscopy, methylation, and UV spectroscopy. The main glycosidic bond structure of this polysaccharide was deduced as follows: the backbone is linked by the glycosidic bond of -*4)alpha-D-Glcp-(1 -* 4)-(3-D-Manp-(1-*, whereas the end group alpha-D-Glcp-(1 -* connects to the backbone via -* 4,6)-(3-DManp-(1 -* O-6. The efficacy of PCLP in treating inflammatory bowel disease (IBD) was subsequently evaluated via an IPEC-J2 cell inflammation model induced by lipopolysaccharide (LPS) and a mouse colitis model induced by dextran sulfate sodium (DSS). PCLP can significantly increase cell viability and upregulate the expression levels of the tight junction proteins ZO-1, Claudin1, Claudin 4 and Occludin, thereby protecting the integrity of the intestinal barrier. Administration effectively alleviated DSS-induced colitis by regulating the composition of the gut microbiota, increasing the quantity of beneficial bacteria and reducing the prevalence of Proteobacteria. PCLP promotes the generation of short-chain fatty acids (SCFAs). These factors play a vital role in maintaining intestinal well-being and suppressing inflammation.