Purification, characterization, simulated gastrointestinal digestion and gut microbiota fermentation of a Bifidobacterium-directed mannoglucan from Lilium brownii var. viridulum

Lilium brownii var. viridulum (Longya lily) is an edible vegetable and medicinal plant with the effects of moistening lungs, relieving coughs, and removing phlegm. In this study, a homogenous mannoglucan LLP11 was purified from Longya lily using membrane ultrafiltration followed by ion exchange chromatography. The Mw of LLP11 was 12.0 kDa. LLP11 exhibited a backbone of →4)-α-D-Glcp-(1 → and →4)-β-D-Manp-(1 → with a branch of T-α-D-Glcp-(1 → substituted at C-6 of →4,6)-α-D-Glcp-(1→. During the simulated digestion, LLP11 remained indigestible to digestive enzymes. Furthermore, through its interaction with the gut microbiota, LLP11 was able to significantly boost Bifidobacterium and decrease the harmful bacteria Klebsiella, that was linked to pneumonia. Additionally, LLP11 promoted the growth of B. pseudocatenulatum and B. longum and was utilized to produce acetic acid. Our findings introduced an alternative approach for the investigation of microbiota-targeted polysaccharides and underscored the potential of LLP11 as a prebiotic for supplementary treatment in respiratory diseases.