Gradual degradation of fucoidan from Fucus vesiculosus and its effect on structure, antioxidant and antiproliferative activities

The fucose-containing sulfated polysaccharides (syn. fucoidans) from brown algae exhibit a wide range of bioactivities and are therefore considered promising candidates for health-supporting and medical applications. During the past three decades, research on isolation, molecular characterization, and screening of in vitro and in vivo pharmacological activities has significantly increased. Until now, however, fucoidans are only used as ingredients in cosmetics and food supplements, especially due to the proclaimed antioxidant activities of fucoidan. One obstacle to medical applications is the usually high molecular mass of native fucoidans, as it is associated with unfavorable biopharmaceutical properties and possibly undesired effects. Therefore, it seems reasonable to develop fucoidan derivatives with reduced size. So far, in this study, fucoidan from Fucus vesiculosus was gradually degraded from M_w 38.2 down to 4.9 kDa without concomitant desulfation. Compared to hydrothermal treatment, the degradation with H₂O₂ showed to be more efficient and additionally eliminated the antioxidant and antiproliferative activities of the genuine fucoidan. This confirmed our previous hypothesis that rather co-extracted compounds like terpenoids and polyphenols than the fucoidan itself exhibit these effects.