In vitro releasing characteristics of bound phenolics from mangosteen ( Garcinia mangostana L.) pericarp dietary fiber and its role in gut microbiota regulation

Bound phenolics interact with dietary fiber through both covalent and non-covalent bonds, but the influence of these interactions on the bioactivity of dietary fiber remains unclear. This study aimed to investigate the releasing characteristic of bound phenolics from mangosteen (Garcinia mangostana L.) pericarp dietary fiber (MDF) and its role in gut microbiota regulation. A self-assembled mixture (DP) constructed with bound phenolics and dephenolized dietary fiber obtained from MDF was severed as control. The results showed the initial content of bound phenolics in MDF was 88.44 +/- 1.10 mg GAE/10 g DW. During gastrointestinal digestion, only 2.04% of bound phenolics was released from MDF. In contrast, colonic fermentation released 12.23% of the bound phenolics. Compared to the DP group, MDF released significantly fewer phenolics during the in vitro gastrointestinal digestion phase, resulting in a higher proportion of bound phenolics entering the colon along with dietary fiber for fermentation. Both MDF and DP were effective in lowering the pH of the fermentation broth, promoting the production of SCFAs, and reducing the F/B ratio in the intestinal flora, compared with the non-fermented group and the fermentation blank control group. However, MDF exhibited more favorable regulatory effects on gut microbiota than DP by up-regulating the abundance of Phascolarctobacterium, Megamonas, and Prevotella, as well as down-regulating the abundance of Escherichia-Shigella. Thus, the present study confirmed the synergistic effect between bound phenolics and dietary fiber, which not only enhanced the bioavailability of bound phenolics, but also strengthened the regulatory function of dietary fiber on intestinal health. This finding provides a scientific basis for optimising dietary structure and promoting intestinal health.