The SeaHealth project was recently launched in France to demonstrate the benefits of seaweeds' antioxidant substances to prevent atherosclerosis and cancer. Antioxidant properties have been reported from Grateloupia filicina, an edible red alga called limu in Hawaiian culture that is widely eaten in Hawaii, Japan, Korea, and other countries. Sulphated polysaccharides from red algae inhibit viral action. Both the Herpes virus (containing DNA) and HIV (containing RNA) are inhibited by sulphated polysaccharides. Aqueous extracts of many red seaweeds are active against retroviruses. Carrageenan is cointernalized into infected cells with Herpes Simplex Virus, thus inhibiting the growth of the virus. Many marine algae have shown antitumor activities. Significant activity against E. coli was found in the brown algae Scytosiphon Iomentaria (69.8% inhibition), Lessonia nigrescens (60%), Laminaria japonica (57.6%), and Sargassum ringgoldainum (46.5%). Five brown and four red algae have shown appreciable antitumor properties against meth-A-fibrosarcoma.
Polysaccharides from brown and red seaweeds have several other uses. Earlier, alginates were used mainly to increase the viscosity of liquids and for dental filling. Today, alginates are being tailor-made by chemical selection or enzymatic treatment. Alginates require calcium, potassium, or sodium for gelation and have limited ranges of textures. Propylene glycol alginate solutions suspend particulates and are used as secondary emulsifiers and flow modifiers for salad dressings and fruit beverages.
Alginates are also used to encapsulate chemical, microbial, plant, and animal cells that are subsequently used as desired metabolite producers. Consumption of sodium alginates and low-molecular sodium alginates reduces cholesterol levels. Brown algal polysaccharides have anticoagulant, antiviral, and anti-inflammatory actions. In clinical trials, simple extracts of Undaria pinnatifida have been potent inhibitors of HIV.
A few companies have successfully demonstrated tank cultivation of Porphyra for the production of specific nutraceuticals Canada-based Ocean Nutrition and Nori Tech, an Israeli company, are developing tailor- made Porphyra to meet specific requirements. In India, Pepsico started large-scale cultivation of carrageenophyte seaweed. With uses for seaweed continuing to expand, the demand for various seaweeds and their products will likely increase in the near future, thereby supporting the need for wider development of pharmacological aquaculture.
BY: DAN BUETTNER
PHOTOGRAPHS BY DAVID McLAIN