A new procedure for determining the heterogeneity of agar polymers in the cell walls ofGracilariaspp. (Gracilariaceae, Rhodophyta)

摘要

The heterogeneity of agar polymers in the cell walls ofGracilaria tenuistipitata,G.eucheumoides, andG.blodgettiiwas demonstrated by sequential extraction of the algae in water at 22 deg;C; in boiling 80, 60, 40, and 20 ethanolndash;water solutions; and in water at 100 and 121 deg;C. Agar polymers in each extract were analyzed by1H and13C nuclear magnetic resonance spectroscopy. The agar polymers extracted from the three algae with water at 22 deg;C had a high concentration of repeat units substituted by alkali-labile sulfate. Methylated agar polymers were extracted with boiling 80 and 60 ethanol fromG.tenuistipitataandG.eucheumoides, the former having a high content of 6-O-methyl-D-galactose and a low concentration of 2-O-methyl-3,6-anhydro-L-galactose and the latter consisting mainly of 2-O-methyl-3,6-anhydro-L-galactose. Sulfated agar polymers (alkali-stable sulfate) were extracted fromG.tenuistipitataandG.blodgettiiwith boiling 20 ethanol and water (100 and 121 deg;C). Floridean starch was detected by13C nuclear magnetic resonance in the extracts fromG.tenuistipitataandG.eucheumoides.