Structural characteristics and bioactivities of polysaccharides from blue honeysuckle after probiotic fermentation

To explore the effect of probiotic fermentation on the structure and property of polysaccharides, three blue honeysuckle polysaccharide (BHP) fractions were extracted and purified from unfermented (BHP–U), Lactobacillus rhamnosus 6224 fermented (BHP-L) and Saccharomyces cerevisiae W5 fermented (BHP–S) blue honeysuckle. The results revealed that fermentation could reduce the molecular weight (MW), increase the galactonic acid content, and change the surface morphology of BHPs. Additionally, structural characterization indicated that BHPs had similar chemical compositions and functional groups and an absence of crystalline and triple helix structures. Moreover, compared with BHP–U, BHP-L and BHP–S exhibited stronger ABTS+ radical scavenging abilities, reducing power (RP), α-amylase inhibitory activity, and TG binding capacity. Unfortunately, fermentation decreased the thermal stability of blue honeysuckle polysaccharides. Finally, the network analysis, which offered a new way to study the structure-activity relationship of BHPs, confirmed that the uronic acid content was positively related to RP (r = 1, p = 0.04) and MW was negatively related to RP (r = −1, p = 0.03). Therefore, BHPs could be used as a potential antioxidant, hypoglycemic, and hypolipidemic agent in medicines and functional foods.