Distinct prebiotic effects of polysaccharide fractions from Polygonatum kingianum on gut microbiota

Abstract

This study investigated the physicochemical properties, digestive stability, and in vitro fermentation behavior of Polygonatum kingianum polysaccharide (PKP) fractions (PKP60, PKP70, PKP80) obtained through graded ethanol precipitation. High-performance gel permeation chromatography revealed significant molecular weight differences among the fractions, while reverse-phase high-performance liquid chromatography indicated consistent monosaccharide types with variations in their proportions. Uronic acid analysis confirmed that all polysaccharide fractions met the criteria for neutral polysaccharides. Congo red staining confirmed the presence of a triple-helix structure in all PKP fractions. Comprehensive analysis demonstrated that these fractions remained stable during in vitro digestion, as evidenced by consistent molecular weights and total carbohydrate content, with no significant production of free monosaccharides or reducing sugars. All PKP fractions were fermented by gut microbiota, resulting in the production of short-chain fatty acids. Beta diversity and structural analyses of gut microbiota revealed distinct modulatory effects associated with each PKP fraction. The PKP fractions promoted probiotic growth, especially PKP70, which significantly enhanced Bifidobacterium proliferation, indicating strong prebiotic potential. These findings underscore the importance of isolation and purification methods in determining the functionality and gut microbiota-modulating effects of plant-derived polysaccharides, emphasizing the need for in-depth research that extends beyond merely evaluating their source.