Impact of biorefinery processing conditions on the bioactive properties of fucoidan extracts from Saccharina latissima on SHK-1 cells

Fucoidans from brown macroalgae exhibit a wide array of bioactivities, from antioxidant to immunostimulatory effects. Their specific effects and efficacy depend on the molecular weight and structure of the polysaccharide chains, which in turn depends on the seaweed species and the methods used for fucoidan extraction and purification. In this study, a bench scale, three factor, three level full factorial experiment was used to determine the relationship between the extraction parameters (duration, hydrochloric acid concentration in extraction liquor, and temperature), the sulfation level and fucoidan yield. Three of the extractions representing the least severe and most severe extractions as well as a calculated sweet spot were scaled up to a pilot biorefinery (5 kg biomass per extraction). To evaluate the potential of using these complex polysaccharides as functional ingredients in salmon aquaculture, bioactivity of the three different fucoidan preparations was examined by in vitro assays with cultures of Atlantic salmon head kidney cells (SHK-1). All pilot extraction products induced an increase in SHK1 cell viability. In addition, “Too careful” also induced an upregulation of il1-β and sod1, both immune-related biomarkers. Interestingly, the expression of these biomarkers showed a positive correlation in SHK-1 cells stimulated with products from both “Too careful” and “Sweet spot” extractions. The data presented here show the extent of shift in bioactivity resulting from changes in the extraction severity in fucoidan biorefining and present the potential for fucoidan application as an immunostimulant for salmon cells.