DOI : https://doi.org/10.4490/algae.2014.29.3.237

Algae. 2014; 29(3): 237-247.

doi: https://doi.org/10.4490/algae.2014.29.3.237

Reevaluation of bactericidal, cytotoxic, and macrophage-stimulating activities of commercially available Fucus vesiculosus fucoidan

Tomoki Nishiguchi¹, Zedong Jiang¹, Mikinori Ueno¹, Satoshi Takeshita², Kichul Cho^3,4, Seong Woon Roh⁴, Kyong-Hwa Kang⁵, Kenichi Yamaguchi^1,6, Daekyung Kim^3,4 and Tatsuya Oda^1,6,*

¹Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki, Nagasaki 852-8521, Japan ²Joint Research Division, Center for Industry, University and Government Cooperation, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki, Nagasaki 852-8521, Japan ³Korea
University of Science and Technology, Daejeon 305-350, Korea
⁴Jeju Center, Korea
Basic Science Institute (KBSI), Jeju 690-756, Korea
⁵Department of Chemistry, Pukyong National University, Busan 608-737, Korea
⁶Division of Biochemistry, Faculty of Fisheries, Nagasaki University, 114 Bunkyo-machi, Nagasaki, Nagasaki 852-8521, Japan

Polysaccharides prepared from marine algae sometimes contain contaminants such as polyphenols and endotoxins that may mislead their bona fide biological activities. In this study, we examined bioactive contaminants in commercially available fucoindan from Fucus vesiculosus, along with ascophyllan and fucoidan from Ascophyllum nodosum. F. vesiculosus fucoidan inhibited the growth of Vibrio alginolyticus in a concentration-dependent manner (0-1,000 μg mL-1). However, the antibacterial activity of the fucoidan significantly reduced after methanol-extraction, and the methanol-extract showed a potent antibacterial activity. The extract also showed cytotoxicity to RAW264.7 and U937 cells, and induced apoptotic nuclear morphological changes in U937 cells. These results suggest that the antibacterial activity of the fucoidan is partly due to the methanol-extractable contaminants that can also contribute to the cytotoxicity on RAW264.7 and U937 cells. On the other hand, the activities to induce secretion of nitric oxide and tumor necrosis factor-α from RAW264.7 cells were observed in the fucoidan even after methanol extraction, and the extract had no such activities. Our observations suggest that commercially available fucoidan should be purified prior to biochemical use.

Keywords : antibacterial activity; contaminants; cytotoxic activity; Fucus vesiculosus; fucoidan