Undaria pinnatifida Fucoidan-Rich Extract Recovers Immunity of Immunosuppressed Mice

We investigated the immune restoration activity of Undaria pinnatifida fucoidan-rich extract in cyclophosphamide-induced immunosuppressed mice. C57BL/6 mice were intraperitoneally injected with 80 mg/kg of cyclophosphamide (CP) and orally administered with either drinking water (DW), red ginseng extract (RG), or one of three different doses of Undaria pinnatifida fucoidan-rich extract (DSU02 50, 100, and 150 mg/kg). After 14 days, liver, spleen, and whole blood were isolated from each animal. The frequencies of NK and CD³⁺, CD⁴⁺, and CD⁸⁺ T cells were significantly increased in splenocytes isolated from the DSU02 100 mg/kg and DSU02 150 mg/kg groups (NK1.1+, 5.4% or 4.9% vs 3.8%; CD³⁺, 39.3% or 37.9% vs 32.3%; CD4+, 22% or 20.2% vs 17.4%; CD8+, 12.7% or 11.6% vs 10.1%). NK cytotoxicity was enhanced in the DSU02-fed groups at all doses (CP-treated DW, 93.4%; RG, 107.2%; DSU02 50, 107.3%; DSU02 100, 107.3%; DSU02 150, 107.1%), and the proliferation of T cells (CD³⁺, CD⁴⁺, and CD⁸⁺) was also greater in the DSU02 100 mg/kg and DSU02 150 mg/kg administered groups compared with the unfed group. Plasma concentrations of TNF-α, IgM, and total IgG from the DSU02 150 mg/kg group were also significantly higher compared with the other groups (TNF-α: CP-treated DW - 21.5 pg/ml, DSU02 150 - 47.1 pg/ml; IgM: CP-treated DW - 82.9 ng/ml, DSU02 150 - 110.8 ng/ml; total IgG: CP-treated DW - 114.4 ng/ml, DSU02 150 - 162.7 ng/ml). We suggest that Undaria pinnatifida fucoidan-rich extract could be a promising candidate for a marine natural immune stimulator.