Characterization of a heterogalactan: Some nutritional values of the edible mushroom Flammulina velutipes

Production and consume of mushrooms have grown in the world, and beside these, the nutritional properties and biological active components of fungi have received more attention by researchers. Considering these, a mannofucogalactan was isolated from Flammulina velutipes, and characterized using ¹³C and ¹H (obs.), ¹³C HMQC nuclear magnetic resonance spectroscopy and methylation analysis. The monosaccharide composition of this polymer was determined by GC–MS and showed Fucp, Manp, and Galp in the molar ratio 20:16:64, respectively. ¹³C NMR and ¹H (obs.), ¹³C HMQC indicated an anomeric region containing signals (C-1/H-1) at δ 102.9/5.19, 102.0/5.16, and 98.8/5.05 corresponding, sequentially, to non-reducing end of α-d-Manp, 3-O-substituted α-l-Fucp, and 6-O- and 2,6-di-O-substituted α-d-Galp units. Along with methylation analysis, these data showed a structure with a main chain composed of 6-O-substituted Galp units, partially substituted at O-2 by 3-O-d-mannopyranosyl-l-fucopyranosyl, α-d-mannopyranosyl, and in a minor proportion, α-l-fucopyranosyl groups. Furthermore, some nutritional values of this edible mushroom were evaluated, like amino acid and mineral nutrient contents.