FVPB1, a novel heteropolysaccharide, was extracted from the Flammulina velutipes fruiting body, and its structure was determined by methylation analysis, nuclear magnetic resonance (NMR) spectroscopy. FVPB1 demonstrated efficacy in inhibiting lipid accumulation in Raw264.7 cells and zebrafish, as well as in reducing weight gain and ameliorating liver injury in high-fat diet-induced mice. High concentration of FVPB1 significantly increased serum ApoA1 levels, while all tested doses (low, medium, and high) reduced serum ApoB levels in mice. Intervention with FVPB1 significantly increased the mRNA expression of Lcat and Cyp7a1 enzymes while markedly reducing the transcriptional level of Hmgcr reductase. Additionally, low concentration of FVPB1 enhanced CYP7A1 protein expression, whereas medium and high concentrations of FVPB1 promoted LCAT protein expression. Medium and high concentrations of FVPB1 significantly enhanced bile acid excretion in mice, with the high dose additionally promoting fecal sterol output. Alpha and beta diversity analyses demonstrated that a high-fat diet induced substantial dysbiosis in the gut microbiota of mice, characterized by reduced microbial diversity and richness. Intervention with FVPB1 significantly modulated the structural composition of the intestinal microbiota in high-fat diet-fed mice. Therefore, FVPB1 exerts lipid-lowering effect in high-fat diet-fed mice by modulating cholesterol metabolism and ameliorating gut microbiota dysbiosis.

The structure and characteristics of LEOPs, β-oligosaccharides from the fruiting body of Lentinus edodes obtained via acid degradation and gel permeation chromatography, were investigated. We performed high-performance liquid chromatography, infrared spectroscopy, methylation analysis, nuclear magnetic resonance, and correlated activity experiments, including antioxidant, immunomodulatory, and liver injury protection to gain insights. LEOPs comprised an oligosaccharide (Mw 2445 Da) based on six β-1, 3-D-glucose residues as the main chain and six β-1, 6-D-glucose residues as the side chain. Surface plasmon resonance analysis indicated that LEOPs directly bound to dectin-1, which facilitated their immunoenhancing activity via downstream NF-κB activation. The results implied that LEOPs may be the active unit of the shiitake β-glucan. The determination of LEOPs structure was performed to reveal the anti-tumor effect and immune-regulatory function of shiitake β-glucan on a molecular level to provide a basis.