Immunomodulatory Activity of Sargassum thunbergii-Derived Glucuronomannan Oligomers: G6 as a Key Bioactive Component.

Cyclophosphamide (CTX) is an anticancer drug known to induce immunosuppression. This study investigated the immunomodulatory effects of Sargassum thunbergii glucuronomannan and its oligomers (Gs) in CTX-induced immunosuppressive mice. Various Gs, including G2, G4, G6, G8, and Gn, were administered to the mice. Among these, G6, G8, and Gn notably improved the spleen index, cytokine levels (IL-2, IFN-γ, NO), and antioxidant activity (SOD, GSH-Px). G6 treatment increased GSH-Px by 29.3% and promoted macrophage viability. Additionally, G6 enhanced mRNA expression of iNOS, IL-2, and TNF-α. Molecular docking analysis and dynamics analysis showed strong interactions between G6 and immune cytokines IL-2 and TNF-α, enhancing receptor-binding efficiency. These results suggested that Gs, particularly G6, played a key role in immunomodulation and might serve as potential candidates.