Unusual partially 3-O-methylated alpha-galactan from mushrooms of the genus Pleurotus

Indistinguishable partially 3-O-methylated galactans were isolated from the edible basidiomycetes Pleurotus eryngii and Pleurotus ostreatoroseus. They were obtained via successive aqueous extraction, freeze-thawing, precipitation with Fehling solution of soluble material, and ultratiltration. Mono- and bidimensional C-13 and H-1-nuclear magnetic resonance spectroscopy (HMBC, HETEROTOCSY, COSY, and HMQC), and methylation analysis were used to determine their structures. They were linear, partially 3-O-methylated, (1 -> 6)-linked alpha-D-galactans containing Gal and 3-Me-Gal, in a 3:1 molar ratio (GC-MS of alditol acetates). (C) 2007 Elsevier Ltd. All rights reserved.