Fucoidan, a major component of brown seaweed, prohibits the growth of human cancer cell lines in vitro.

Fucoidan, the general term for sulfated polysaccharides, is reported to engage in various biological activities having anti-tumor, anti-coagulation and anti-viral effects. Though it has been investigated, the mechanism of its anti-tumor effects remains elusive. The current study examined the anti-tumor effects of fucoidan extracted from Okinawa mozuku on 15 human cancer cell lines (6 hepatocellular carcinomas, 1 cholangiocarcinoma, 1 gallbladder cancer, 2 ovarian cancers, 1 hepatoblastoma, 1 neuroblastoma and 3 renal cancers) using an MTT assay. Changes in apoptosis and the cell cycle were analyzed by flow cytometry. The results revealed that cell proliferation was suppressed in 13 cell lines in a time- and/or dose-dependent manner; this suppression was marked in the hepatocellular carcinoma, cholangiocarcinoma and gallbladder carcinoma cell lines. In contrast, proliferation of the neuroblastoma and 1 of the 2 ovarian carcinoma cell lines was not affected. The ratio of apoptotic cells significantly increased in 5 of the 6 hepatocellular carcinoma cell lines, and the ratio of G2/M cells increased in the 3 hepatocellular cell lines examined. These observations indicate that fucoidan is a potential anti-tumor agent for the treatment of bile duct cancers, such as hepatocellular carcinoma, cholangiocarcinoma and gall-bladder carcinoma.