Structure characterization and in vitro hypoglycemic effect of partially degraded alginate

Alginate is a low-cost polysaccharide found abundantly in seaweeds which consists of mannuronate and guluronate, and it is considered a sustainable gum source for dietary fiber. To solve the high viscosity-related problems while retaining its physiological properties, four partially degraded alginate products (PDA1-4) with molecular weight of 1.05-0.40 x 105 g mol-1 and intrinsic viscosity of 170.9-38.9 mL g-1 were enzymatically prepared and characterized. 1H Nuclear magnetic resonance analysis showed the used alginate lyase had a preference to degrade guluronate-blocks. PDA1 and PDA2 presented random coil conformation, whereas PDA3 and PDA4 displayed compact spherical-coil conformation over random coil conformation in solution. In vitro assays suggested a glucose-adsorption capacity order of PDA1 < PDA2 < alginate < PDA3 < PDA4 and a glucosediffusion retardation capacity order of PDA3 < PDA1 <= alginate < PDA2 < PDA4, indicating that partially degraded alginate reinforced the hypoglycemic effect, especially mannuronate-rich PDA4. Overall, the study may have important implications for development of PDA as dietary fiber with potential hypoglycemic activity.

Automated summary

Alginate, a low-cost polysaccharide found in seaweeds, is considered a sustainable gum source for dietary fiber. Partially degraded alginate products may enhance the hypoglycemic effect, especially mannuronate-rich PDA4, suggesting potential implications for development as dietary fiber with hypoglycemic activity.