Structure-function relationships of Ganoderma polysaccharides: extraction, classification, bioactivities, and gut microbiota modulation.

Ganoderma spp. Polysaccharides (GPs) are structurally diverse bioactive macromolecules with significant therapeutic potential, including antioxidant, antidiabetic, hepatoprotective, immunomodulatory, and prebiotic effects mediated through gut microbiota modulation. This review comprehensively summarises the extraction, structural characteristics, and biological activities of GPs, with a particular focus on their structure-function relationships and translational applications. Structurally, GPs are primarily composed of glucans along with heteroglucans and heterogalactans, where molecular weight and branching patterns play a crucial role in determining biological activity. Various extraction strategies, including enzymatic, ultrasound-assisted, and microwave-assisted procedures, have been developed to increase polysaccharide recovery yield and efficiency. Preclinical experimental evidence from in vitro and animal studies suggests that GPs have significant antioxidant and metabolic-regulating effects. GLP demonstrated strong antioxidant action with an IC₅₀ of 0.56 mg/ml (ABTS assay), and antidiabetic investigations found a considerable drop in blood glucose levels to 162.8 ± 24.67 mg/dL at 50 mg/kg. Additionally, GPs enhanced gut microbial metabolism, with short-chain fatty acid levels reaching 361.37 μg/mg, indicating improved intestinal homeostasis. Mechanistically, GPs regulate oxidative stress, immune responses, and gut microbiota composition, contributing to their multifunctional biological activities. Collectively, it highlights the integrated relationship between structural properties and biological functions of GPs and supports their potential application in functional foods and nutraceutical development targeting metabolic and gastrointestinal health.