Figure 1.

Isolation and purification of carrageenans and their structural features. The dried algae were soaked in 96% alcohol and then underwent water extraction three times. The obtained extracts were combined, filtered, and centrifuged at 2500× g, 10 °C for 20 min. Polysaccharides were precipitated with three times greated volume of 95% ethanol. The resulting substance was a fraction of the total carrageenan. A 4% KCl solution is added to the polysaccharides, followed by centrifugation (10,000× g, 30 min, 4 °C). The obtained supernatant contains soluble KCl fraction − λ carrageenan (λ-polysaccharide). The fraction insoluble in KCl represented κ-carrageenan (κ-polysaccharide). We performed sonication for depolymerization of initial κ- and λ-carrageenan polysaccharides. The resulting samples of carrageenan oligosaccharides (κo- and λo-) were dialyzed and freeze-dried.