Structural Characterization, Physicochemical Properties, and Ameliorating Effect on Age-Related Constipation of an Arabinogalactan from Peach Gum.

Peach gum (PG), a resin secreted from Prunus persica or Prunus davidiana, is used to support gut health. In this study, an arabinogalactan, PG-2, was isolated and purified from PG. The structural and physicochemical properties of PG-2 were analyzed. The efficacy of PG-2 in alleviating constipation and its effects on gut microbiota, its metabolites, colonic 5-HT production, and 5-HT-mediated signaling pathways were evaluated using a humanized aging constipation model. PG-2 has a molecular weight of 3185.2 kDa, with (1→3,6)-linked β-d-galactosyl and (1→5)-linked α-l-arabinosyl residues as the major residues. PG-2 exhibits a loose mesh-like structure with shear thinning, thermal stability, water-binding ability, and moderate surface activity. PG-2 was found to enhance the abundance of gut microbiota like Ruminococcus and facilitate the production of tryptophan metabolites like tryptamine, which activates the gut 5-HT signaling pathway, thereby alleviating elderly constipation. In summary, PG-2 represents a promising functional food or an active ingredient for protecting the gastrointestinal tract.