Antioxidant potential of the bio-based fucose-rich polysaccharide fucopol supports its use in oxidative stress-inducing systems

Reactive oxygen species (ROS) are dangerous sources of macromolecular damage. While most derive from mitochondrial oxidative phosphorylation, their production can be triggered by ex-ogenous stresses, surpassing the extinction capacity of intrinsic antioxidant defense systems of cells. Here, we report the antioxidant activity of FucoPol, a fucose-rich polyanionic polysaccharide produced by Enterobacter A47, containing ca. 17 wt% of negatively charged residues in its struc-ture. Ferric reducing antioxidant power (FRAP) assays coupled to Hill binding kinetics fitting have shown FucoPol can neutralize ferricyanide and Fe3+-TPTZ species at an EC50 of 896 and 602 µg/mL, respectively, with positive binding cooperativity (2.52 ≤ H ≤ 4.85). This reducing power is greater than most polysaccharides reported. Moreover, an optimal 0.25% w/v FucoPol concentration shown previously to be cryo-and photoprotective was also demonstrated to protect Vero cells against H2O2-induced acute exposure not only by attenuating metabolic viability decay, but also by accentuating post-stress proliferation capacity, whilst preserving cell morphology. These results on antioxidant activity provide evidence for the biopolymer’s ability to prevent positive feedback cascades of the radical-producing Fenton reaction. Ultimately, FucoPol provides a biotechnological alternative for implementation in cryopreservation, food supplementation, and photoprotective sunscreen formula design, as all fields benefit from an antioxidant functionality.