Comparison of chemical property and in vitro digestion behavior of polysaccharides from Auricularia polytricha mycelium and fruit body

Abstract

The antioxidant activity of Auricularia polytricha is associated tightly with its polysaccharide concentration, molar mass and architecture. This study aims to explore the differences in structural and physicochemical traits and oxidation resistances between the polysaccharides from fruit body (ABPs) and mycelial (IAPs) of Auricularia polytricha. The results showed that ABPs and IAPs were constituted by glucose, glucuronic acid, galactose and mannose. However, the molecular weight distribution of IAPs (3.22 × 104 Da (52.73%) and 1.95 × 106 Da (24.71%)) was wider than that of ABPs (5.4 × 106 Da (95.77%)). The shear-thinning performance and viscoelastic behavior of both IAPs and ABPs are representative. IAPs are scattered in sheets, with folds and holes, and have a triple helix structure. ABPs are compact in structure and clear in texture. The main functional groups and thermal stability of both polysaccharides were similar. Concerning the in-vitro oxidation resistance, both of the studied polysaccharides exhibited the potent potential to scavenge hydroxyl radicals (IC50 = 3.37 ± 0.32 and 6.56 ± 0.54 mg/mL, respectively) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals (IC50 = 0.89 ± 0.22 and 1.48 ± 0.63 mg/mL, respectively), as well as the moderate reduction power. In addition, IAPs and ABPs were both completely undigested in simulated contexts of saliva, small intestine and stomach, and the two polysaccharide types maintained high DPPH and hydroxyl radical scavenging activities. DDPH scavenging rate during digestion was positively correlated with uronic acid content. To conclude, this study suggests the potential of IAPs as an equivalent alternative to ABPs.