Polysaccharide extracted from peony seed meal preventive effect of on loperamide-induced constipation in rats.

In the present study, one polysaccharide (named PSP-1) was purified from peony (Paeonia suffruticosa Andr.) seed meal, and its structural characteristics, as well as preventive constipation activity, were investigated. The weight average molecular weight of PSP-1 was 15.3 kDa and was composed of arabinose, galactose, glucose, xylose, and mannose in the molar ratio of 1:4.8:5.1:0.4:0.2. The primary structure of PSP-1 was elucidated through Fourier-transform infrared spectroscopy (FT-IR) and methylation analysis, revealing its glycosidic linkages and branching pattern. In the loperamide-induced constipated rat, PSP-1 significantly increased fecal parameters and accelerated intestinal transit (69 min reduction). PSP-1 enhanced total short-chain fatty acid (SCFAs) production by 9.1 %, particularly propionic and butyric acids. Furthermore, PSP-1 had a bidirectional effect on gastrointestinal hormones: it increased the serum levels of motilin, gastric inhibitory polypeptide, and substance P by 12.8 %, 13.0 %, and 13.4 %, respectively, while decreasing the levels of secretin and vasoactive intestinal polypeptide by 21.7 % and 17.6 %, respectively. Additionally, 16S rRNA sequencing indicated that PSP-1-mediated gut microbiota rebalances, suppressing pathogens and enriching beneficial genera. These findings suggested that PSP-1, a natural plant extract, maybe a dietary supplement that helps prevent constipation, providing a theoretical reference for its application in functional foods.