The system of sulfated galactans from the red seaweed Gymnogongrus torulosus (Phyllophoraceae, Rhodophyta): Location and structural analysis

José M. Estevez, Marina Ciancia, Alberto S. Cerezo

Resultado de la investigación: Contribución a una revistaArtículorevisión exhaustiva

20 Citas (Scopus)

Resumen

Sulfated polysaccharides were localized in the cuticle, cortex and medulla of the gametophyte thallus, being more concentrated in the intercellular matrix than in the cell walls. During the water extraction sequence, a small percentage of galactan sulfates (5.1% of dry seaweed) with average low Mr (6-11.4 kDa) were extracted at room temperature without disturbing the cellular arrangement, while sulfated galactans of average medium Mr (18-45 kDa) were obtained by further hot-water extractions (52.4% of dry seaweed), with diorganization of the tissue. The residue (40.0% of dry seaweed) still contained carrageenan-type (major) and agaran-type (minor) galactans. Part of these galactans was extracted with 8.4% LiCl solution in DMSO, from which "pure" κ/ι-carrageenans were isolated. Carrageenans and agarans were extracted in a ratio 1:0.5, showing the highest amount of agaran-structures for a carrageenophyte. The galactans comprise alternating 4-sulfated (major) and non-sulfated (minor) 3-linked β-d-galactopyranose units, and 4-linked α-galactopyranose units with the following substitutions: (i) non-sulfated and 2-sulfated 3,6-anhydro-α-d-galactopyranose residues in the carrageenan-structures, which belong to the κ-family (κ/ι-carrageenans); (ii) 3-sulfated α-l-galactopyranose units and 2-sulfated 3,6-anhydro-α-l-galactopyranose residues in the agaran-structures. Alkaline treatment and alkaline dialysis of the main extracts gave "pure" κ/ι-carrageenans, showing that carrageenan molecules are extracted together with low Mr agarans or agaran-dl-hybrids.

Idioma originalInglés
Páginas (desde-hasta)594-605
Número de páginas12
PublicaciónCarbohydrate Polymers
Volumen73
N.º4
DOI
EstadoPublicada - 5 sep 2008
Publicado de forma externa

Áreas temáticas de ASJC Scopus

  • Química orgánica
  • Polímeros y plásticos
  • Química de los materiales

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