This study aimed to evaluate the influence of ultrasonic degradation on the physicochemical and biological characteristics of Polygonatum cyrtonema polysaccharide (PCP, 8.59 kDa). PCP was subjected to ultrasonic treatment for 8, 16, and 24 h and yielded the degraded fractions PCP-8, PCP-16, and PCP-24 (5.06, 4.13, and 3.69 kDa), respectively. Compared with the intact PCP, PCP-8, PCP-16 and PCP-24 had a reduced particle size (decrements of 28.03 %, 46.15 % and 62.54 %, respectively). Although ultrasonic degradation did not alter the primary structure of PCP, its triple helical and superficial structures were disrupted, with degraded fractions demonstrating reduced thermal stability and apparent viscosities compared with those of the intact PCP. Furthermore, the functional properties of the degraded fractions were different. PCP-16 most favourably affected GLP-1 secretion, while PCP-8 and PCP-24 exhibited the strongest antioxidant and enzyme inhibitory activities, respectively. Hence, controlled ultrasound irradiation is an appealing approach for partially degrading PCP and enhancing its bioactivity as a functional agent.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized inflammatory imbalance, intestinal epithelial mucosal damage, and dysbiosis of the gut microbiota. Polygonatum cyrtonema polysaccharides (PCPs) can regulate gut microbiota and inflammation. Here, the different doses of PCPs were administered to dextran sodium sulfate-induced UC mice, and the effects of the whole PCPs were compared with those of the fractionated fractions PCP-1 (19.9 kDa) and PCP-2 (71.6 and 4.2 kDa). Additionally, an antibiotic cocktail was administered to UC mice to deplete the gut microbiota, and PCPs were subsequently administered to elucidate the potential role of the gut microbiota in these mice. The results revealed that PCP treatment significantly optimized the lost weight and shortened colon, restored the balance of inflammation, mitigated oxidative stress, and restored intestinal epithelial mucosal damage. And, the PCPs exhibited superior efficacy in ameliorating these symptoms compared with PCP-1 and PCP-2. However, depletion of the gut microbiota diminished the therapeutic effects of PCPs in UC mice. Furthermore, fecal transplantation from PCP-treated UC mice to new UC-afflicted mice produced therapeutic effects similar to PCP treatment. So, PCPs significantly ameliorated the symptoms, inflammation, oxidative stress, and intestinal mucosal damage in UC mice, and gut microbiota partially mediated these effects.

Polysaccharides, the major active ingredient and quality control indicator of Polygomatum cyrtonema are in need of elucidation for its in vitro fermentation characteristics. This study aimed to investigate the structural characteristics of the homogeneous Polygomatum cyrtonema polysaccharide (PCP-80 %) and its effects on human intestinal bacteria and short chain fatty acids (SCFAs) production during the in vitro fermentation. The results revealed that PCP-80 % was yielded in 10.44 % and the molecular weight was identified to be 4.1 kDa. PCP-80 % exhibited a smooth, porous, irregular sheet structure and provided good thermal stability. The analysis of Gas chromatograph-mass spectrometer (GC-MS) suggested that PCP-80 % contained six glycosidic bonds, with 2,1-linked-Fruf residues accounted for a largest proportion. Nuclear magnetic resonance (NMR) provided additional evidence that the partial structure of PCP-80 % probably consists of →1)-β-D-Fruf-(2 → as the main chain, accompanied by side chains dominated by →6)-β-D-Fruf-(2→. Besides, PCP-80 % promoted the production of SCFAs and increased the relative abundance of beneficial bacteria such as Megamonas, Bifidobacterium and Phascolarctobacterium during in vitro colonic fermentation, which changed the composition of the intestinal microbiota. These findings indicated that Polygomatum cyrtonema polysaccharides were able to modulate the structure and composition of the intestinal bacteria flora and had potential probiotic properties.