Induction of degradation of fucoidan oligosaccharides via low-temperature plasma treatment for enhanced structural characteristics and bioactivities

Low-temperature plasma (LP) is an emerging advanced oxidation technology that can rapidly and efficiently degrade refractory organic compounds without introducing secondary pollutants. Further investigation is required into the mechanisms of polysaccharide degradation via plasma technology and the enhancement of the bioactivity of the resulting degradation products. In this study, we systematically investigated the degradation mechanisms, structural transformations, and functional potential of fucoidan (Fuc) using LP technology. The critical parameters of the LP treatment were optimized based on the Box–Behnken design, leading to the successful preparation of Fuo-30 T. Kinetic analysis revealed that the degradation process of Fuc followed second-order reaction kinetics. Structural characterization demonstrated that the active radicals generated by LP preferentially cleave glycosidic bonds in glucuronic acid (Glc p A) residues and β-1,6-linked side chains. Fuo-30 T significantly improves DSS-induced colitis. Mechanistically, it inhibits the activation of the NF-κB and MAPK pathways, enhances the stability of Nrf2 and PPARγ, and effectively reduces oxidative stress and inflammatory responses. Another possible mechanism involves lipid metabolism, particularly that of arachidonic acid. Fuo-30 T intervention significantly decreased the production of proinflammatory factors (PGE2, TXB2, and Hete) by inhibiting the cyclooxygenase and lipoxygenase pathways, thereby improving the TCA cycle. Finally, Fuo-30 T significantly upregulated the expression of tight junction proteins in the intestinal epithelium by reshaping the gut microbiota structure, which synergistically improved intestinal microecology and mucosal immune homeostasis.