Use of solid and gel state 13C NMR spectroscopy for differentiation between agarophytes and carrageenophytes

Abstract

Both solid state (CP-MAS) and gel state (using standard solution state conditions) 13 C NMR spectroscopy have been used to characterize a range of red algae that produce either agar or carrageenan . These techniques allow rapid determination of phycocolloid type within the algal tissue before extensive and time-consuming extractions and fractionations are carried out .The gel state technique can be used on living or dried material . Gel state spectra give high resolution and, because of the expectation that they will be correlated with the extractable phycocolloid, provide promise of a powerful technique for screening potentially useful red algae .

Structural, Physical, and Chemical Modifications Induced by Microwave Heating on Native Agar-like Galactans

“…Because of the typical low concentration of this type of residues in agars from Gracilaria further 1D 13 C attached proton tests (APTs) were performed with more scans than the previous 13 C spectra in order to check for the existence of typical signals of acetal C. No methyl, acetal, or carbonyl carbons could be detected in the APT spectrum (data not shown). Therefore, we concluded that no traceable amounts of pyruvated G segments existed in the extracts and that the signal around (1.30; 30) ppm could be related with nongalactan signals . No detectable starch contamination was found in native agars from IMTA seaweed (absence of typical C NMR signals of (1 → 4) (1 → 6)-α- d -glucan) contrary to wild G. vermiculophylla from French waters…”

“…Therefore, we concluded that no traceable amounts of pyruvated G segments existed in the extracts and that the signal around (1.30; 30) ppm could be related with nongalactan signals. 22 No detectable starch contamination was found in native agars from IMTA seaweed (absence of typical C NMR signals of (1 → 4) (1 → 6)-α-D-glucan) 4 contrary to wild G. vermiculophylla from French waters. 23 FTIR analysis showed typical bands of agar-like galactans and were well related with NMR results.…”

Physical state of κ-carrageenan modulates the mode of action of κ-carrageenase from Pseudoalteromonas carrageenovora

“…-Carrageenan forms physical gels in vitro that mimic the conformational and physical properties of algal cell walls [51,52]. By definition, gels are not as well organised as highly crystalline materials such as cellulose, chitin or starch.…”

Solid-State NMR Investigations of Extracellular Matrixes and Cell Walls of Algae, Bacteria, Fungi, and Plants

“…Several fucose-containing sulfated polysaccharides called fucoidans have been reported in brown algae and exhibited antioxidant or anti-inflammatory activities. , Agar units can also be sulfated or methylated at different positions, giving furcellaran, funoran, porphyran, and carrageaenan, which have been differentiated using 13 C ssNMR. − Solid-state NMR has also been conducted to separate agars and carrageenans extracted from red algae …”