Structural Characterization of Water-Soluble Pectin from the Fruit of Diospyros lotus L. and Its Protective Effects against DSS-Induced Colitis in Mice

Polysaccharides from Diospyros lotus L. were investigated for their structural characterization and anti-inflammatory activity. Four low polymer dispersity index (PDI) subfractions were obtained: DRP-1 (153.95 kDa), DRP-2 (61.22 kDa), DRP-3 (22.80 kDa), and DRP-4 (8.93 kDa), respectively. DRP-4 contained the highest number of RG-I domains (43.25%), while DRP-1 had the highest degree of methyl esterification (37.5%). Results from the dextran sulfate sodium (DSS) salt-induced ulcerative colitis (UC) mice model indicated that DCP promoted mucosal and tight junction protein (caudin-1 and occludin) expression. Moreover, DCP improved the microbial community composition through selective enrichment of beneficial bacteria such as Lachnospiraceae and Lactobacillaceae. The anti-inflammatory activity of DCP was speculated to be related to its neutral sugar side chain and low esterification degree. These results suggested that DCP could prevent DSS-induced colitis and inhibit colon inflammation by maintaining a balanced gut microbiome and protecting the colon mucosal barrier.