2. University of the Ryukyus, Health and Longevity Research Laboratory, Integrated Innovation Research Centre, Nishihara, Okinawa 903-0213, Japan.
3. Gifu University, Department of Applied Bio-organic Chemistry, Gifu, Gifu 501-1193, Japan.
A rare sugar, 6-deoxy-D-altrose, isolated from a polysaccharide extracted from an edible folk medicinal mushroom (Lactarius akahatsu) was identified using 1H and 13C-NMR including 2D-COSY and 2D-HSQC spectroscopy, and specific rotation. The 6-deoxy-sugar isolated from the acid hydrolysate of the polysaccharide extracted from L. akahatsu was involved in four anomeric isomers (α- and β-pyranose, and α-and β-furanose) in aqueous solution due to mutarotation. Almost all of the signals from the 1D (1H- and 13C-) and 2D (COSY and HSQC)-NMR spectra of the 6-deoxy-sugar agreed with the data from the authentic 6-deoxy-D-altrose. The specific rotation [α]589 of the 6-deoxy-sugar isolated from L. akahatsu was +17.6°. Thus, the 6-deoxy-sugar isolated from Lactarius akahatsu was identified as 6-deoxy-D-altrose.
Keywords: Lactarius akahatsu, folk medicinal mushroom, 6-deoxy-D-altrose, rare sugar, polysaccharide moiety