, Volume 204, Issue 1, pp 645–654 | Cite as

Agaroids from New Zealand members of the Gracilariaceae (Gracilariales, Rhodophyta) — a novel dimethylated agar

  • Richard H. Furneaux
  • Ian J. Miller
  • Thomas T. Stevenson
Chemical structure


Polysaccharide extracts from four New Zealand members of the Gracilariaceae have been characterized by 13C-NMR spectroscopy and GLC analysis of alditol acetate derivatives prepared using a new double hydrolysis-reduction procedure. All were based on variously substituted repeating disaccharide units of agarobiose and ≤ 20% of its ‘precursor’ containing l-galactose-6-sulfate. Gracilaria truncata yielded a firm gelling agar with 67% methylation on the 6-position of the d-galactose residues. The other extracts belong to a new class of agar molecules having methylation on both the 6-position of the d-galactose units and the 2-position of the l-sugar units. The Curdiea coriacea polysaccharide displayed this double methylation almost completely (≥ 96 %); the alkali-modified polymer thus had only two free hydroxy-groups per disaccharide repeat unit, yet still gave a firm gel. The Curdiea flabellata and Melanthalia abscissa extracts had this double methylation pattern but to a lesser extent, and additional xylosyl branch units on up to 18% of the repeating disaccharide units.

Key words

agar composition Curdiea coriacea Curdiea flabellata Gracilaria truncata Gracilariaceae Melanthalia abscissa polysaccharide seaweed 


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Copyright information

© Kluwer Academic Publishers 1990

Authors and Affiliations

  • Richard H. Furneaux
    • 1
  • Ian J. Miller
    • 1
  • Thomas T. Stevenson
    • 1
  1. 1.DSIRChemistry DivisionPetoneNew Zealand

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