Gracilariopsis hommersandii, a red seaweed, source of agar and sulfated polysaccharides with unusual structures

RODRÍGUEZ SÁNCHEZ, RODRIGO A.; FISSORE, ELIANA N.; CIANCIA, MARINA; COSENZA, VANINA A.; MATULEWICZ, MARÍA C.; CANELÓN, DILSIA J.; GERSCHENSON, LÍA N.

CARBOHYDRATE POLYMERS

ELSEVIER SCI LTD

Año: 2019 vol. 213 p. 138 - 146

0144-8617

Red seaweed Gracilariopsis hommersandii produces important amounts of non-gelling galactans, which were extracted with hot water (GrC, yield, 37%, viscosity average molecular weight, Mv 109 kDa), comprising agarose and sulfated galactan structures. The alkali modified derivative, GrCTr (Mv 95 kDa), gave a galactose:3,6-anhydrogalactose molar ratio of 1.0:0.9, and a more regular structure, favouring gelation (melting and gelling temperatures 64 and 14 °C, respectively). The rheological properties of this product suggest possible applications as hydrocolloid. G. hommersandii also biosynthesizes non gelling sulfated galactan fractions with diads constituted by β-D-galactose and partially cyclized α-L-galactose units or non-cyclized α-D-galactose residues. Sulfation was mainly detected on C6 or C4 of the β-D-galactose units, and on C6 and, in minor amounts, on C3 of the α-L-galactose units. The presence of β-apiuronic acid was demonstrated for these fractions as side chains of the galactan backbone. Carrageenan structures were found for the first time in an agarophyte of the Gracilariales.