The application of C-13 NMR spectroscopy to the red algal polysaccharides of selected New Zealand species of Lomentaria

摘要

The structural features of polysaccharides extracted from four New Zealand species of Lomentaria were examined. The polysaccharides retain the expected backbone structure of alternating 3-linked and 4-linked galactosyl units, with the 4-linked units containing some 3,6-anhydro-L-anhydrogalactose and galactose in the D- (40%) and L- (60%) configurations. Natural sulfation leads to twelve different units being found. Since none of the levels of 3-linked units matched those of 4-linked units, many units were in at least two different diads, and with such variation it is unlikely that there is a consistently repeating structure as such. An important diad combined 4-linked L-galactose-2,3-disulfate and L-galactose 2,3,6-trisulfate with 3-linked D-galactose-2,6-disulfate, a diad group equivalent to the principal diad in Champia polysaccharides with primary hydroxyl groups sulfated. A further important diad is 3-linked D-galactose-2,4-disulfate with 4-linked D-galactose-3-sulfate, a diad group also found in Hymenocladia sanguinea. Hence these results suggest that Lomentaria has an intermediate relationship with respect to Champia and Hymenocladia within the Rhodymeniales.