Background: We showed that fucoidan, extracted from dietary seaweed, could inhibit tumor growth. However, the mechanism of Mekabu (Sporophyll of Undaria pinnatifida) fucoidan antitumor activity and how it enhances the immune response remains unknown.
Materials and methods: We examined the effect of Mekabu fucoidan in P-388 tumor-bearing mice and in T cell-mediated NK cell activity in normal mice.
Results: The survival of mice was prolonged when Mekabu fucoidan was administered for 4 days before tumor cell inoculation, compared with non-treated mice. Fucoidan significantly enhanced the cytolytic activity of NK cells and increased the amount of IFN-gamma produced by T cells up to about 2-fold compared with non-treated mice.
Conclusion: The anti-tumor effect of Mekabu fucoidan appears to be mediated by IFN-gamma-activated NK cells.