Comparative study of physicochemical properties, antioxidant activity, antitumor activity and in vitro fermentation prebiotic properties of Polyporus umbellatus (Pers.) Fries polysaccharides at different solvent extractions

Polyporus umbellatus (Pers.) Fries (PU), a medicinal fungus, contains polysaccharides (PUPs) as its primary bioactive components. In this paper, physicochemical properties, biological activities and in vitro fermentation prebiotic properties of PUPs, extracted by 90 °C hot water (PUP-W), 0.9 % NaCl (PUP-N), citric acid (PUP-S) and 0.1 M NaOH (PUP-A) were compared. The PUPs were composed of multiple monosaccharides, with significant differences in chemical composition and structure. The extracted PUPs demonstrated notable antioxidant, antitumor and prebiotic activities. With the highest yield (2.96 ± 0.12), PUP-A exhibited better biological activities due to its small molecular weight. The antioxidant ability (clearing DPPH (IC 50  = 0.64) and ABTS free radicals (IC 50  = 1.23)) of PUP-A was strong, so was the ability of ROS clearing. PUP-A significantly decreased the cell survival rate of HepG2 (IC 50  = 1090). In terms of prebiotic properties, both PUP-N and PUP-A showed substantial promoting effects on some beneficial bacteria, like Bacteroidetes at the phylum level and Lactobacillus at the genus level. In summary, our study suggests that alkali is the better solvent and provides new insights into the relationship between the structure, biological activities, and gut microbiota of PUPs, laying the foundation for better development of the role of PU.