Structural and compositional characteristics of hybrid carrageenans from red algae Chondracanthus chamissoi

Two polysaccharides CCC and CCH were extracted from red algae Chondracanthus chamissoi by cold water and hot water, respectively. Characterization of the structure by chemical and spectroscopic methods showed that CCC was a hybrid carrageenan composed of κ-carrageenan (35%) and ι-carrageenan (43%) along with its precursor μ-carrageenan (22%) and CCH was an ideal κ-carrageenan. Oligosaccharides from CCH and CCC were prepared and their structural sequences determined by ES-CID-MS/MS gave further insight into the structural characteristics of hybrid carrageenans from C. chamissoi. Some hybrid oligosaccharides, e.g., κ–κ, κ–μ and κ–ι, were obtained with mild acid hydrolysis of CCC. Then, a regular even-numbered oligosaccharides generated with reductive acid hydrolysis of CCH confirmed it an ideal κ-carrageenan.