Title : Macroalgae: An interesting source of highly diversified specific polysaccharides – PSAMAL project
Abstract:
Seaweed are used by coastal populations for centuries for their high nutritional value, but today represents a major economic development challenge. Macroalgae are a high-potential renewable bioresources with a fast-growing value-added market. Among many bioactive components derived from algae, glycans are polysaccharides of variable size, distinguished by their multiple properties, especially antioxidant, antimicrobial, anticarcinogenic, immunostimulant and anti-inflammatory ones. These algal polysaccharide bioactivities are mainly attributed to the complex, highly branched polymeric structures and specific chemical compositions, including sulfated groups. For example, galactans and fucoidans are sulfated polysaccharides of interest.
Thus, algal polysaccharides show great potential for applications in the food and feed, pharmaceutical, phytosanitary, nutraceutical and cosmetic sectors, justified by the attraction of active ingredients of natural origin.Nevertheless, despite their potential to generate numerous high value-added products and biomolecules, algae remain under-utilized in Europe.
The present work focuses on the evaluation of polysaccharidic content (carrageenan, xylan, galactan, fucoidan) of three macroalgae cultivated in our regions (Opalgue project), two species of red algae, i.e. Palmaria palmata (PP) and Porphyra purpurea (PU), and a brown one, Saccharina latissima (SL). Various extractions and treatments were carried out. Conventional maceration-type extractions in H2O/Ethanol mixtures at 40°C, 150rpm for 4h and polysaccharide-selective extractions in H2O at 80°C, 150rpm for 2h were compared. Total phenolic and flavonoic content (TPC and TFC), total sugars and sulfates were determined using UV spectrophotometric methods, as well as polysaccharidic chemical characterization.
For example, the selective polysaccharide treatment condition provided significant total sugar quantities up to 764 mgEG/gDE (mg glucose equivalent/g dry extract) instead of 400 mgEG/gDE in non-selective aqueous extraction in Porphyra extract. At the same time, the antioxidant activities of every extract were carried out. These extracts are currently tested for their antimicrobial, antifungal and biostimulant activity (Malgabio project). In the near future, tests to obtain oligosaccharides from algal polysaccharides will be carried out in the laboratory, by chemical, mechanochemical and enzymatic processes.
