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Laminaran or Laminarin, is a brown seaweed polysaccharide found in plastids of the cells. It is a linear polysaccharide mainly in a form of β-(1–3)-d-glucans with the branches of β-(1–6)-D-glucosyl, and at the ends of the polymeric chains d-mannitol or d-glucose residues are seen (Figure 4.6). The ratio of each chain and structure are varying from species to species and with growth environment conditions. The main laminarin-rich seaweed species are Laminaria, Saccharina, Ascophyllum and Fucus. Laminaria and its derivatives, sulfated laminaran and oligo-laminaran which are obtained by chemical modifications, are biologically active.

The extraction procedure (Figure 4.7) is in many pathways [65, 69, 78, 79]. Laminaran is extracted together with the alginate and fucoidan and exactly needs purification steps. Calcium chloride added extraction is preferred to prevent solubilization of alginate, and because of being smaller molecular weight, laminaran can be separated from fucoidan by using ultrafiltration [11, 76, 77]. There is also a water extraction and a centrifugation for purification step, to precipitate alginate and fucoidan together.

Figure 4.6 Laminaran structure with (a) d-mannitol and (b) d-glucose residues.

Figure 4.7 Laminaran extraction procedure.

Laminaran is a nonfood grade polysaccharide like fucoidan. Nevertheless, laminaran is used as a dietary fiber supplementation. Because of its oligo-structure it is used by the microbial 0biota in gut which helps to prevent colon cancer [80–82]. The main applications are in clinical and pharmaceutical, mainly in cancer treatments, for its activities of anticoagulant, antimetastatic and tumor inhibiting activities. Laminaran, in cosmeceutical application, is used to increase the rate of the production of reconstructed dermis [83].