Fucoidan, like many seaweeds, has been consumed for a long time in Asian countries, and also used as a nutraceutical and cosmeceutical all around the world. Due to the biological activities, such as anticoagulant, antithrombotic, antitumor, antivirus, anti-proliferative, anti-inflammatory etc. their application interest is high in biological and life sciences. One of the application areas is as a dietary supplement as capsules and a powder supplement for beverages to enhance the immune system. In food industry, these sulfated polysaccharidecontained seaweeds, which have a prebiotic property, are used as a food supplementary for nutritional and functional food formulation. Anticoagulant, antimicrobial and anti-biofilm activities of fucoidans are used in dental applications. The ability to absorb directly by the human skin, as a cosmeceutical in topical cosmetics, fucoidans are used for whitening, preserving moisture, removing freckles in cosmetic industry [11, 60, 71–77].
4.1.5 Laminaran
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].
4.1.6 Ulvan
Ulvan is a sulfated cell-wall polysaccharide of the green algae, Ulva sp. It is mainly made up of l-rhamnose, d-xylose, d-glucose, d-glucuronic acid [11] and small amounts of sulfate groups positioned in xylose and rhamnose units [84–86].
To date ulvan is the less studied and investigated seaweed polysaccharide. Ulvan’s rheological properties are attractive and because of this, ulvan is considered as a food-grade polysaccharide [29]. It has a unique gel-forming mechanism, quiet complex and not yet understand, which make ulvan viscous than Arabic gum. Ulvan polymers and oligomers have comprehensive biological and pharmacological activities, such as antioxidant, antihyperlipidemic, proliferation, adhesion, anti-tumoral and anti-influenza [11, 30, 85–86]. In formation of biodegradable films, ulvan has an application area, for minimizing the microbial population.
4.2 Conclusion
Seaweeds are used as a sustainable resource in the production of high-value compounds, whose commercialization potential has increased in recent years, still have compounds to be discovered. High-value compounds obtained from seaweeds; fat and fatty acids, proteins, carbohydrates (sugars), pigments, minerals, vitamins, sterols, antioxidants and bioactive polyphenols are successfully found applications in pharmaceutical, food and healthcare, etc. industries.
Among several seaweed polysaccharides, their biological (biocompatibility, cell adhesion, cell proliferation, gel-forming ability, collagen matrix formation) and techno-functional (emulsification, gelation, foaming) properties based on its unique structure. With the increasing concern for “natural” and “functional” material for pharmaceutical, food and medical applications, seaweed polysaccharides are seen great interest.
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