Studies on antioxidative and immunostimulating fucogalactan of the edible mushroom Macrolepiota dolichaula

• A water soluble fucogalactan was isolated from the mushroom Macrolepiota dolichaula.
• Its structure was established by chemical and 1D/2D NMR experiments.
• This fucogalactan showed antioxidant properties in different in vitro test systems.
• This fucogalactan also exhibited immunoenhancing activity.

A water soluble fucogalactan (PS-II) of an average molecular weight ∼1.2×105 Da was isolated from the aqueous extract of an edible mushroom Macrolepiota dolichaula. It was composed of fucose, galactose and 3-O-methyl galactose in a molar ratio of nearly 1:4:1. Structural characterization of PS-II was carried out using total hydrolysis, methylation analysis, Smith degradation, and 1D/2D NMR experiments. These results indicated that the proposed repeating unit of the PS-II had a backbone chain consisting of four (1→6)- linked α-d-Galp residues, one residue methylated at O-3, and another one substituted at O-2 by (1→2)-α-d-Galp residue, which is terminated with a α-l-Fucp moiety. The PS-II exhibited the antioxidant properties in different in vitro test systems, and also showed in vitro macrophage activation in RAW 264.7 cell line as well as splenocyte and thymocyte activation in mouse cell culture medium.

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