Exploring the Structure–Activity Relationship of <i>F. velutipes</i> Polysaccharide: A Novel Promising Anti-Inflammatory and Intestinal Barrier-Protective Molecule Extracted by Ultrasound

Ultrasonic extraction has the advantage of higher efficiency in the extraction of <i>F. velutipes</i> polysaccharides (FVP), but the structure and activities with application value of FVP extracted by ultrasound (FVPUs) were unclear. FVPUs were separated into FVPU1 and FVPU2 and subjected to structural analysis, anti-inflammatory activity, and intestinal mucosal protection activity research. Compared to FVPU1, FVPU2 exhibited a higher molecular weight, smaller crystallinity index, higher contents of galactose, mannose, and fucose, a more stable triple helix structure, and stronger binding ability to Congo red and calcium ions. The research disclosed that FVPU2 demonstrated significant activity in alleviating the abnormal surge of NO, IL-1β, IL-6, and TNF-α. This outcome was accomplished through the suppression of the overactive TLR4/MyD88/NLRP3 signaling pathway. Furthermore, FVPU2 decreased the death rate of intestinal cells and enhanced the expression of Occludin, ZO-1, trefoil factor-3 (TFF-3), epidermal growth factor (EGF), and prostaglandin E synthase 2 (PTGES2) (<i>p</i> < 0.05). This study sought to advance the comprehension of the relationship between the structure and anti-inflammatory and intestinal protection activities of <i>F. velutipes</i> polysaccharides, contributing valuable insights to the field of food science.