Related Experiment Video
Updated: Jul 7, 2026

Valorization of the Red Seaweed Gracilaria gracilis Through a Biorefinery Approach
Published on: November 21, 2023
Agarans from the red seaweed Polysiphonia nigrescens (Rhodomelaceae, Ceramiales)
Héctor J Prado1, Marina Ciancia, María C Matulewicz
1Departamento de Química Orgánica, CIHIDECAR-CONICET, Facultad de Ciencias Exactas y Naturales, UBA, Pabellón 2, Ciudad Universitaria, 1428EGA Buenos Aires, Argentina.
Abstract:
Polysiphonia nigrescens was sequentially extracted with water at room temperature, 70 and 90 degrees C. The extracts were analyzed and the major one, isolated at 70 degrees C, was fractionated by ion-exchange chromatography, eluting with water and solutions of increasing sodium chloride concentration; five main fractions were separated. Structural analysis, carried out by methylation analysis and NMR spectroscopy, showed that four of these were partially cyclized agarans that were highly substituted on C-6 mainly with sulfate, although methyl ether and single stubs of beta-D-xylose were found in minor proportions. A fifth fraction comprising 6-sulfated agarose was also isolated. The use of 2D NMR techniques allowed us to assign the 1H and 13C NMR resonances of the G6S-->L6S diad for the first time.
Related Concept Videos
Red Algae
Other Algae
Green Algae
Diversity of Protists III
Overview of Algae
Non-vascular Seedless Plants

