A polysaccharide extracted from Astragalus membranaceus residue improves cognitive dysfunction by altering gut microbiota in diabetic mice

A novel polysaccharide named as AERP was extracted from industrial Astragalus membranaceus-extracted waste residue, which was composed of two components coded as AERP1 and AERP2. The structures of AERP1 and AERP2 were determined by HPLC-SEC-RID, HPLC-C18-UV, FT-IR, and NMR. The results showed that AERP1 was an acidic component with a molecular weight of 2.01 × 106 Da and glycosidic bonds of →3/5-α-araf-(1→, T-α-araf, →4,6-β-manp-(1→, →3/3,6-β-galp-(1→, →2/2,4-α-rha-(1→, →-4/4,6-α-glcp-(1→, →4-α-galpA-(1→ and →4)-6-OMe-α-galpA-(1→. AERP2 was a glucan with 2.11 × 103 Da by →4/6-α-glcp-(1→ linkage. In vitro, AERP retarded glucose diffusion significantly than each single component. In vivo, AERP had a hypoglycemic effect on db/db diabetic mice by alleviating the hyperglycemia, tissue impairment, and inhibiting cognitive impairment. AERP could alter the gut microbiota and modulate the composition of SCFAs. This study gives an opportunity for exploring the industrial waste of Astragalus membranaceus in diabetic complication therapy.