Isolation, Purification, and Characterization of a Polysaccharide from Armillaria mellea and Its Ameliorative Effects on Scopolamine-induced Memory Impairment in Mice

Background Scopolamine-induced cognitive impairment is associated with oxidative stress and neurotransmitter dysregulation, and the neurocognitive effects of Armillaria mellea polysaccharide AMP-A-1 remain unclear. Purpose This study aimed to investigate whether AMP-A-1 could ameliorate scopolamine-induced cognitive deficits in mice, providing a foundation for its potential therapeutic applications. Materials and Methods A water-soluble polysaccharide (designated as AMP-A-1, with an average molecular weight of 3.5 kDa) was obtained from the aqueous extract of A. mellea through sequential purification using DEAE-cellulose-52 and Sepharose CL-6B chromatographic columns. Its composition was analyzed, revealing 95.68% neutral sugar, 2.56% protein, and 1.78% uronic acid, with mannose, GlcA, Rha, GalA, and Glc in a molar ratio of 0.51:1.03:1.82:0.75:95.89. In vivo experiments assessed the effects of AMP-A-1 on systemic oxidative status by measuring serum activities of key antioxidant enzymes and lipid peroxidation products, as well as neurotransmitter levels (gamma-aminobutyric acid [GABA], acetylcholinesterase [AChE], glutamate [GLU], acetylcholine [ACh], and choline acetyltransferase [ChAT]) in brain tissue using scopolamine-induced cognitive impairment models. Results AMP-A-1 markedly enhanced the activity of key antioxidant enzymes and decreased lipid peroxidation in murine serum. In brain tissue, it decreased GABA and AChE levels while elevating GLU, ACh, and ChAT levels. AMP-A-1 demonstrated a notable improvement in scopolamine-induced learning and memory deficits. Conclusion The cognitive-enhancing effects of AMP-A-1 may be attributed to its ability to activate ChAT, increase ACh levels, and enhance antioxidant enzyme activity. These results indicate that AMP-A-1 has potential as a functional dietary ingredient to enhance cognitive performance.