Structural characterization of almond polysaccharides (Armeniaca Sibirica L. Lam) and the prebiotic effects on human...

In this study, the prebiotic effect of polysaccharide AS-3 extracted from almond (Armeniaca Sibirica L. Lam) on the intestinal flora of healthy individuals was investigated. Structural characterization determined AS-3 has a molecular weight of approximately 51 kDa. Its composition includes arabinose, galactose, rhamnose, glucose, and glucuronic acid, adopting a triple helical structure. Detailed linkage analysis via NMR and methylation studies identified a primary backbone featuring →3,6)-α-D-Gal-(1→, →3)-β-D-Gal-(1→, and →5)-α-L-Araf-(1 → units. Branching occurs at the O-6 position of →3,6)-α-D-Gal-(1 → residues. Compared to inulin, AS-3 consistently yielded greater microbial diversity during both 24-h and 48-h fermentation experiments. GC-MS analysis confirmed that AS-3 significantly boosts beneficial short-chain fatty acids (SCFAs), particularly acetic acid and butyric acid. It also selectively stimulated beneficial bacteria while suppressing potentially harmful ones. Significantly, AS-3 lowered the Firmicutes/Bacteroidetes ratio, suggesting a role in promoting gut balance. These findings support AS-3's potential for functional food applications targeting gut microecological health.