Structural characterization and protective effect against murine sepsis of fucogalactans from Agaricus bisporus and Lactarius rufus

► Fucogalactans RFP-Ab and RFP-Lr showed similar main structure. ► RFP-Lr showed a highest fucose content, while RFP-Ab presented β-Galp. ► Both fucogalactans promoted the reduction in late mortality rate by 62.5% and 50%. ► The increase in tissue MPO was significantly prevented by both fucogalactans. Fucogalactans from edible Agaricus bisporus (RFP-Ab) and wild Lactarius rufus (RFP-Lr) mushrooms were obtained on aqueous extraction followed by purification. RFP-Ab had Mw 43.8×104gmol−1 and RFP-Lr Mw 1.4×104gmol−1. RFP-Lr had a (1→6)-linked α-d-Galp main-chain partially substituted at O-2 by nonreducing end-units of α-l-Fucp (29%). While RFP-Ab had a similar main chain, it was partially substituted at O-2 by nonreducing end-units of α-l-Fucp (2.8%) and β-d-Galp (14.5%), and partially methylated at HO-3. Both RFP-Lr and RFP-Ab were tested in mice against polymicrobial sepsis. Lethality rate, myeloperoxidase (MPO) activity and cytokine levels were determined. It was observed a reduction in late mortality rate by 62.5% and 50%, respectively, prevention of neutrophil accumulation in ileum and decreasing in TNF-α and IL-1β serum levels.