Intestinal immunostimulating effects of a grape pomace polysaccharide fraction and structural changes in an...

In this study, we investigated the immunostimulatory activity and structural characteristics of grape pomace polysaccharide (GPP). In both in vitro and in vivo experiments, GPP markedly enhanced the immune responses of Peyer's patches, an effect was accompanied by increased levels of cecal short chain fatty acids. Compositional sugar and glycosidic linkage analyses identified GPP as a complex polysaccharide comprising yeast-derived glucan, mannan, and grape peel-derived pectin. In the artificial digestion model, glucan and pectin were largely degraded, whereas mannan retained its indigestible structure. Further fractionation by ion exchange and size exclusion chromatography revealed that the neutral sugar fractions (glucan and mannan) played a significant role in macrophage activation. Collectively, these findings demonstrated that GPP not only stimulated innate immunity, including Peyer's patches and macrophages, but also served as an energy source for the gut microbiota, thereby exerting beneficial effects on the intestinal environment, highlighting its applicability in functional food.

The online version contains supplementary material available at 10.1007/s10068-026-02151-7.