Synergistic regulation of crude Sphallerocarpus gracilis polysaccharides and probiotics on intestinal flora and its immune-related metabolites in rats.

BACKGROUND

Sphallerocarpus gracilis (SG) is a medicinal and edible plant in China with high nutritional value. In the present study, the synergistic effect of crude Sphallerocarpus gracilis polysaccharides (CSGP) and specific probiotics on the intestinal flora and its immune-related metabolites in rats was investigated. Probiotic fermented milk supplemented with 5-15 g L-1 CSGP (YSGP) was prepared. Following a 60-day feeding experiment conducted on Wistar rats, the levels of inflammatory factors in the serum were measured, and the contents of intestinal metabolites, including short-chain fatty acids, indole, 3-methylindole and hydrogen sulfide, were assessed. Additionally, the changes in the fecal microbiota were analyzed using 16S rRNA high-throughput sequencing.

RESULTS

The results demonstrated that YSGP containing ≥10 g L-1 CSGP significantly modulated the intestinal flora by increasing the relative abundance of Bacteroidetes, Lactobacillaceae, Erysipelotrichaceae, Prevotella and Turiubacter, at the same time as reducing the relative abundance of Firmicutes, Ruminococcaceae and Dorea (P < 0.05). The levels of short-chain fatty acids (acetic acid, propionic acid, butyric acid, isobutyric acid and valeric acid), indole derivatives and serum cytokines [tumor necrosis factor-α, interleukin (IL)-6, IL-8 and IL-1β] in rats were also enhanced after YSGP consumption (P < 0.05). Correlation analysis revealed strong positive associations between CSGP, beneficial microbial abundance, intestinal metabolites and cytokine levels.

CONCLUSION

These findings demonstrate the prebiotic capacity of CSGP to synergize with probiotics in regulating intestinal microecology and immunity, highlighting its potential application in functional fermented dairy products. © 2025 Society of Chemical Industry.