Immunomodulatory and Antioxidant Activities of Selenium-Enriched Polysaccharides from Epimedium and Isatis Indigotica

This study aims to investigate the effects of selenium modification on polysaccharides derived from two traditional Chinese medicinal herbs-Epimedium (Yinyanghuo) and Isatis root (Banlangen)-in enhancing immune function and antioxidant activity. The purpose is to explore the relationship between structure and function, providing a theoretical basis for the development of efficient plant-based functional antioxidants. Polysaccharides were extracted using an optimized enzymatic hydrolysis method and subsequently selenized using sodium hydrogen selenite, resulting in selenized Epimedium Polysaccharides (sEPS) and selenized Isatis Root Polysaccharides (sIRPS). Structural characterization was performed using infrared spectroscopy, UV spectroscopy, and thermogravimetric analysis. Antioxidant capacity was evaluated via ABTS radical scavenging assay, while immune-enhancing activity was assessed through Peripheral Blood Mononuclear Cell (PBMC) proliferation assays in vitro. The selenium modification retained the primary glycosidic backbone while enhancing both antioxidant and immunomodulatory activities. ABTS scavenging results showed that sIRPS samples achieved up to 35.26% clearance at 1 mg/mL concentration, with several samples maintaining high activity even at lower concentrations (p<0.05). PBMC proliferation experiments demonstrated that both sEPS and sIRPS significantly increased cell proliferation across multiple doses, with sIRPS7 showing the best performance in the medium-dose group (p<0.05). The selenium-modified polysaccharides from Epimedium and Isatis root exhibit significantly enhanced immune and antioxidant functions, with evident dose dependence. Unlike previous studies focusing on single-source selenium polysaccharides, this study establishes a comparative evaluation model under a unified experimental system, thereby expanding the application potential of organic selenium polysaccharides in functional foods and herbal therapeutics.