CELL-WALL POLYSACCHARIDES FROM AUSTRALIAN RED ALGAE OF THE FAMILY SOLIERIACEAE (GIGARTINALES, RHODOPHYTA) - IOTA KAPPA/BETA-CARRAGEENANS FROM MELANEMA-DUMOSUM/

The cell wall galactan from Melanema abumosurn (Harvey) Min-Thein et W omersley collected from south-eastern Australia was extracted (46% w/w yield) and analysed by chemical and physical methods. The preparation has a high sulphate ester content (26.9% w/w as SO3Na) and the domina nt constituent sugars of the sample are galactose and 3,6-anhydrogalac tose in approximately equimolar proportions. Small amounts of xylose a nd glucose are also present. No mono-O-methylgalactose or pyruvate was detected. Evidence from infrared and C-13-nuclear magnetic resonance spectroscopy indicates that the polysaccharide is a hybrid or mixture of iota (iota)-, kappa (kappa)- and beta (beta)-carrageenans. The chem istry of the polysaccharide from M. dumosum is compared with that of p olysaccharides from species of the Solieriaceae and the Caulacanthacea e. We conclude from the polysaccharide data that, although Melanema du mosum may not be closely allied to the genera Areschougia, Rhabdonia a nd Erythroclonium, it can be retained provisionally in the family Soli eriaceae, although its possible inclusion in the Caulacanthaceae canno t be dismissed.