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

Abstract

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 Fuc p, Man p, and Gal p 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-Man p, 3- O-substituted α- l-Fuc p, and 6- O- and 2,6-di- O-substituted α- d-Gal p units. Along with methylation analysis, these data showed a structure with a main chain composed of 6- O-substituted Gal p 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.