In Vitro Gastrointestinal Digestion of Polyonatum cyrtonema Polysaccharides and Impact on Intestinal Flora

Abstract

Polyonatum cyrtonema polysaccharides (PCPs) have been illustrated to have pharmacological and biological activity. However, the impact of PCPs on gut microorganisms and their metabolic pathways has been scarcely addressed. In order to investigate the antidigestion potential of PCPs, an in vitro simulation of digestion was developed. Moreover, an in vitro fermentation model was used to explore the influence of PCPs on the microbial community. The findings revealed that the concentration of the remaining carbohydrate and reducing end of the polysaccharide chain grew slightly, while the molecular weight was unaltered after being digested. Notably, the gut microbiota degraded the PCPs during the subsequent fermentation, resulting in the production of short-chain fatty acids and a significant decrease in the pH level ($p<0.05$). Compared with the control group, the result of 16S rRNA sequencing revealed that PCPs could affect the diversity of the community and the composition of the gut microbes significantly ($p<0.05$), having similar regulatory effects to inulin on the structure of the microbial community. The PCPs group notably promoted the relative abundance of acetic-acid bacteria, such as Bifidobacterium. In addition, PICRUSt2 analysis demonstrated that PCPs mainly enhanced phenotypic KEGG pathways such as amino acid metabolism and carbohydrate metabolism. Overall, PCPs may have prebiotic properties that support human health by controlling the make-up and metabolic activity of intestinal flora.