Relationship between molecular weights and biological properties of alginates extracted under different methods from Colpomenia peregrina

The effect of extraction methods using water, acid, Alcalase and Cellulase was studied on structure bioactivity relationship of alginates from Colpomenia peregrina. Enzyme-assisted extractions produced alginates with the lowest protein (< 0.7%) and polyphenol (< 5 mg gallic acid/g sample) contaminations. The molecular weight (M-W) of alginate extracted after acid treatment was 386.4 x 10(3) g/mol. The minimum M-W of 247.9 x 10(3) g/mol was determined for alginates extracted after Cellulase treatment. The specific volume of gyration (SVg) increased to > 0.57 cm(3)/g in enzymatically treated alginates. Alginate isolated after Cellulase treatment was nontoxic and stimulated RAW264.7 macrophage cells to release nitric oxide and inflammatory cytokines such as TNF-alpha, IL-1, IL-6, IL-10 and IL-12. The DPPH radical scavenging activity and reducing power were shown to be the highest for enzyme-treated. This study demonstrates the lab scale feasibility of extraction of alginate with the highest immunomodulatory and antioxidant properties.