Low-molecular-weight fucoidan prepared by ultrasonic/H2O2/VC degradation: Characterization, gut microbiota regulation, and anti-inflammatory effects

Fucoidan, a marine-derived sulfated polysaccharide, possesses a diverse range of bioactive properties. This study aimed to evaluate the physicochemical characteristics and anti-inflammatory activity of Laminaria japonica fucoidan (LJF) and degradation fractions (DLJF-Ts) obtained through ultrasonic-assisted H 2 O 2 /Vitamin C (VC) treatment (1, 3, and 6 h). The molecular weights of LJF, DLJF-1, DLJF-3, and DLJF-6 were 225, 101, 45, and 31 kDa, respectively. The fucose was the major monosaccharide, and structural analysis demonstrated that the main functional groups were unchanged, while their sheets changed from larger to smaller. Meanwhile, the DLJF-3 showed the superior effects of in vitro antioxidant and anti-inflammatory. Furthermore, after 48 h of colitis mice fecal fermentation, the DLJF-3 was metabolized by gut microbiota, leading to a marked elevation in short-chain fatty acids. The content of Bacteroides increased and the Desulfovibrio reduced significantly. Overall, the obtained results revealed that DLJF-3, as the anti-inflammatory agent, could be used for the development of functional foods and healthcare products.