Structural characterization of fructans from Polygonatum kingianum and their effects on LOP-induced constipation in mice.

Polygonatum kingianum, a renowned traditional Chinese medicine and functional food rich in polysaccharides and other health benefits. In this study, three neutral fructants named PKF-2, PKF-3, and PKF-4 were purified from P. kingianum. Results showed that all of them were composed of fructose and glucose, with the degrees of polymerization (DP) of 25, 14, and 9, respectively. Structural analysis suggested that the fructans shared a core structure featuring an α-glucose unit (→6)-α-D-Glcp-(1→), extended by fructose chains linked via β-(2 → 1)- and β-(2 → 6)-glycosidic bonds. Pharmacological evaluation in a loperamide-induced murine constipation model demonstrated that PKF administration significantly alleviated constipation symptoms. This was evidenced by increased fecal output and gastrointestinal transit rate compared to the Lop model group. Furthermore, PKF normalized serum levels of key regulatory factors, such as MTL, GAS. Additionally, PKF protected against Lop-induced intestinal barrier damage and modulated critical pathways involved in motility (SCF/c-Kit) and fluid homeostasis (AQP/ENaC-γ). Notably, PKF elicited comparable or superior therapeutic effects to the positive control lactulose (2.5 g/kg) at significantly lower doses (100-400 mg/kg). These findings establish a theoretical foundation for the potential applications of low molecular weight carbohydrate compounds derived from P. kingianum.