Preparation, antioxidant and immunomodulatory activities of selenium-modified galactomannan.

In this study, selenylation modification of Gleditsia sinensis galactomannan (GSG) was carried out using the HNO3-Na2SeO3 method, successfully yielding the selenylated product (SeGSG). Structural characterization confirmed that selenium was introduced into the GSG chain via the formation of C-O-Se covalent bond at the C6-hydroxyl sites. This modification altered the polymerization degree and structure of GSG, thereby significantly enhancing its in vitro antioxidant capacity. Biological assays demonstrated that SeGSG exhibited markedly lower developmental toxicity in zebrafish than Na2SeO3, indicating improved biosafety. In an LPS-induced zebrafish inflammation model, SeGSG effectively alleviated oxidative stress and liver injury. This protective effect was attributed to the modulation of antioxidant-related genes (Sod-2, Gclc) and immune-related genes (NF-κB, IL-1β), which subsequently lowered reactive oxygen species and nitric oxide levels. This study demonstrates that selenylation modification significantly enhances the bioactivity and biosafety of GSG, providing an experimental foundation for developing SeGSG as a novel functional food ingredient.