STRUCTURAL FEATURES DRIVE BIOACTIVITY OF PECTIC POLYSACCHARIDES FROM POTATO/ IMMUNOMODULATION AND GUT MICROBIOME MODULATION

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Abstract
Pectin comprises homogalacturonan (HG) and rhamnogalacturonan-I (RG-I). High molecular weight (Mw) pectin can be hydrolyzed into smaller pectic polysaccharides (PPS), offering different solubility and viscosity.We investigated how structural differences influence the bioactivity of potato-derived PPS fractions. Direct immunomodulatory effects were evaluated using a Caco-2/PBMC coculture model, while indirect, microbiome-mediated effects were evaluated via ex vivo colonic fermentation using the ex vivo SIFR® technology, coupled to the same immune model.Both PPS fractions were enriched in RG-I, in contrast to apple pectin, which was HG-rich and characterized by higher galacturonic acid and lower galactose content. High Mw PPS exhibited higher acetylation, whereas low Mw PPS showed more galactan branching. Both PPS fractions induced moderate cytokine responses under basal conditions (healthy state), while attenuating LPS-induced secretion of pro-inflammatory cytokines, effect likely related to their low degree of methyl-esterification. Both PPS fractions were utilized by gut microbes, resulting in increased short-chain fatty acid (SCFA) production and selective enrichment of beneficial taxa. PPS elicited stronger bifidogenic effects than apple pectin. Fermentation-mediated immunomodulatory effects mirrored those of the non-fermented compounds.PPS distinctly shaped the gut microbiome and host immunity depending on their structural features, supporting a structure-guided approach for selecting health targeting ingredients.