The sulfated modification of polysaccharide from Poria cocos and its prebiotic effects on gut microbiota.

Background: Poria cocos is a renowned medicinal and edible macrofungus in China. Alkali-soluble polysaccharide from Poria cocos (PCY) is one of its main active components. However, the biological activity and utilization of PCY are constrained by its poor water solubility. Therefore, we modified PCY with chlorosulfonic acid-pyridine to improve its properties in this study. By comparing the results of solubility, antioxidant and hypoglycemic assays, we chose one derivative for further studies, which was named PCY-S2. We simulated in vitro the digestion and microbial fermentation of PCY-S2 using feces from volunteers and then gavaged it to mice to investigate its impacts on gut microbial modulation.

Results: The results showed that PCY-S2 could effectively regulate gut microbiota in fecal fermentation and animal experiments. In in vitro microbial fermentation, PCY-S2 upregulated the abundance of probiotic bacteria such as Streptococcus, Bifidobacterium and Lactococcus. In in vivo microbial studies, PCY-S2 downregulated the ratio of Firmicutes to Bacteroidota at the phylum level, significantly increasing the relative abundance of several beneficial microbiota such as unclassified_f_Muribaculacea, Prevotellaceae_UCG-001 and Alloprevotella at the genus level. Also, it promoted short-chain fatty acid production and reduced the levels of IL-6 and TNF-α.

Conclusion: Overall, PCY-S2 is beneficial for regulating the composition and structure of gut microbiota, which provides a candidate for developing an effective functional prebiotic. © 2025 Society of Chemical Industry.