Abstract:The modification of Dendrobium officinale polysaccharide (DOP) with selenium and the immune-regulating activity of selenated Dendrobium officinale polysaccharide (SeDOP) were investigated. The preparation of SeDOP was optimized using a combination of single-factor experiments and response surface methodology. The immunomodulatory activity of SeDOP was assessed using RAW 264.7 cell proliferation models and immunosuppressed animal models induced by cyclophosphamide. The results indicated that the optimal preparation conditions for SeDOP were as follows: reaction temperature of 72 ℃, mNa2SeO3: mDOP=1.1, the nitric acid volume fraction of 0.6%, and reaction time of 7.2 h, resulting in a selenium content in SeDOP of 1.55 mg/g. Cell proliferation assays demonstrated a dose-dependent enhancement of RAW 264.7 cell proliferation by both DOP and SeDOP at a concentration of 200 μg/mL; DOP and SeDOP increased cell proliferation rates by 132.9% and 175.4%, respectively. Animal experiments demonstrated that DOP and SeDOP increased the immune organ index in experimental mice compared to the model group. Serum levels of IL-2, TNF-α, and IFN-γ were significantly elevated in the DOP group, reaching 155.3, 184.2, and 152.9 pg/mL, respectively. In the SeDOP group, the values were 316.2, 385.2, and 208.2 pg/mL. H&E staining of the spleen indicated that SeDOP at medium and high doses significantly alleviated spleen damage induced by cyclophosphamide. Overall, SeDOP exhibited notable immunomodulatory activity, surpassing the effects of pure DOP. This study provides a theoretical foundation for developing and applying selenium-modified DOP and selenium supplements.
