**Background:** Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by mucosal inflammation of the colon, with clinical manifestations including diarrhea, abdominal pain, bloody stools, and weight loss. Current clinical treatments (aminosalicylates, corticosteroids, thiopurines, anti-TNF-α drugs) have significant side effects with long-term use. Polysaccharides from natural sources have gained attention as potential therapeutic agents due to their biodegradability, non-toxicity, and biocompatibility. Pinus yunnanensis pollen has been used in traditional Chinese medicine, but the effects of its polysaccharides on UC had not been studied. This study aimed to evaluate the effects of PPM60 and its sulfated derivative SPPM60 on DSS-induced UC in mice from the perspectives of intestinal immunity, serum metabolomics, and gut microbiota.
**Methods:** PPM60 was extracted from broken Pinus yunnanensis pollen using water extraction and 60% ethanol precipitation, followed by protein removal. SPPM60 was prepared via chlorosulfonic acid-pyridine sulfation. Monosaccharide composition was analyzed by HPLC, and structural characterization was performed by FT-IR spectroscopy. Forty SPF male C57BL/6 mice were randomly divided into four groups (n=10): healthy control (HC), DSS model, PPM60-treated (PM, 200 mg/kg/day), and SPPM60-treated (SPM, 200 mg/kg/day). UC was induced using 3% DSS in drinking water for 5 days, followed by normal water. Polysaccharides were administered daily by intragastric administration for 7 days. Disease activity index (DAI) was calculated daily based on weight loss, stool consistency, and blood in stool. Colon tissues were examined histologically by H&E staining. Cytokine levels (IL-1β, IL-6, TNF-α, IL-2, IL-10, IL-13, sIgA) in colon tissue and serum CRP and D-lactic acid were measured by ELISA. Serum metabolomics was analyzed using 1H-NMR spectroscopy with multivariate statistical analysis (PCA, PLS-DA, OPLS-DA). Gut microbiota in feces and cecum contents was analyzed by 16S rDNA amplicon sequencing.
**Key Results:** PPM60 was composed of galactose, glucose, xylose, mannose, rhamnose, and an unknown monosaccharide in molar ratios of 12.830:10.449:29.693:1:1.415:1.426. The sulfate substitution degree of SPPM60 was 1.45. DSS-induced UC mice showed significant weight loss (>20% by day 7), colon shortening (4.7 ± 0.28 cm vs. 6.7 ± 0.18 cm in HC), and severe mucosal damage. PPM60 and SPPM60 partially ameliorated colon shortening (PM: 5.2 ± 0.09 cm; SPM: 5.6 ± 0.17 cm) and reduced histological damage. In the DSS group, pro-inflammatory cytokines (IL-1β, IL-6, TNF-α) were increased, while anti-inflammatory cytokines (IL-2, IL-10, IL-13) were decreased. PPM60 and SPPM60 reversed these trends, with SPPM60 showing slightly stronger effects. Serum CRP was elevated in the DSS group and inhibited by both treatments. Serum D-lactic acid was reduced in PM and SPM groups. Metabolomic analysis revealed that PPM60 mainly regulated energy-related metabolic pathways (pyruvate metabolism, glycolysis/gluconeogenesis), while SPPM60 primarily regulated lipid-related metabolic pathways (glycerophospholipid metabolism, glycine/serine/threonine metabolism). Gut microbiota analysis showed that DSS reduced OTU numbers (958 in cecum, 906 in feces vs. 1117 and 1019 in HC). PPM60 and SPPM60 partially restored species diversity. Both treatments reduced harmful bacteria (Akkermansia, Aerococcus) and increased beneficial bacteria (Lactobacillus). SPPM60 also reduced Turicibacter abundance.
**Clinical Implications:** This study provides the first evidence that Pinus yunnanensis pollen polysaccharides and their sulfated derivatives can ameliorate DSS-induced UC in mice through multiple mechanisms, including reducing intestinal inflammation, regulating serum metabolism, and restoring gut microbiota balance. The differential effects—PPM60 targeting energy metabolism and SPPM60 targeting lipid metabolism—suggest potential for tailored therapeutic applications. These findings provide an experimental basis for developing plant polysaccharides as adjuvant clinical treatments for UC. However, further research is needed to determine which form (PPM60 or SPPM60) is more effective and to translate these findings to human clinical applications.