ANTITUMOR-ACTIVITY AND IMMUNOLOGICAL PROPERTIES OF MARINE ALGAL POLYSACCHARIDES, ESPECIALLY FUCOIDAN, PREPARED FROM SARGASSUM-THUNBERGII OFPHAEOPHYCEAE

Marine algal polysaccharide, GIV-A from Sargassum thunbergii markedly inhibited the growth of Ehrlich ascites carcinoma at the dose of 20 mg /kg per day X10 with no sign of toxicity in mice. GIV-A is suggested t o be a hexouronic acid containing L-fucan sulfate, fucoidan by the ana lyses of physicochemical properties and IR-and NMR-spectra. The result s of carbon clearance activity with fucoidan demonstrated that it is a cting as a so-called activator of the reticuloendothelial system. Fuco idan enhanced the phagocytosis and chemiluminescence of macrophages. B y the immunofluorescent method, binding of the third component of comp lement (C3) cleavage product to macrophages and the proportion of C3 p ositive cells were increased. In crossed immunoelectrophoresis, human serum C3 was converted by fucoidan and appeared as the 3rd peak (conve rted C3). The height of the 3rd peak was directly proportional to the doses of fucoidan. The residual CH50 units of human serum decreased do se-dependently. These results suggest that the antitumor activity of f ucoidan is related to the enhancement of immune responses. The present results indicate that fucoidan may open new perspectives in cancer ch emotherapy.