Simulated digestion, dynamic changes during fecal fermentation and effects on gut microbiota of Avicennia marina (Forssk.) Vierh. fruit non-starch polysaccharides

Grey mangrove (Avicennia marina (Forssk.) Vierh.) fruit is a traditional folk medicine and health food consumed in many countries. In this study, its polysaccharides (AMFPs) were obtained and analyzed by chemical and instrumental methods, with the results indicating that AMFPs consisted of galactose, galacturonic acid, arabinose, and rhamnose in a molar ratio of 4.99:3.15:5.38:1.15. The dynamic changes in AMFPs during the digestion and fecal fermentation processes were then investigated. The results confirmed that AMFPs were not depolymerized by gastric acid and various digestive enzymes. During fermentation, 56.05 % of the AMFPs were utilized by gut microbiota. Galacturonic acid, galactose, and arabinose from AMFPs, were mostly consumed by gut microbiota. AMFPs obviously decreased harmful bacteria and increased some beneficial microbiota, including Megasphaera, Mistuokella, Prevotella, and Megamonas. Furthermore, AMFPs obviously increased the levels of various short-chain fatty acids. These findings suggest that AMFPs have potential prebiotic applications for improving gut health.