In vitro and in vivo antioxidant activities of a fucose-rich fucoidan isolated from Saccharina japonica

The antioxidant activity of previously purified fucoidan fraction, LJSF4, from Saccharina japonica were evaluated in Vero cells and zebrafish. LJSF4 effectively reduced intracellular reactive oxygen species (ROS), apoptosis, and cell death stimulated by 2,2-azobis(2-amidinopropane) hydrochloride (AAPH) in Vero cells. Further studies indicated that the antioxidant activity was caused by up-regulating catalase and superoxide dismutase levels in AAPH-treated Vero cells. In addition, LJSF4 significantly suppressed AAPH-induced oxidative damage in zebrafish by improving survival and heartbeat disorder of the zebrafish embryo as well as reducing the levels of ROS, cell death, and lipid peroxidation in AAPH-treated juvenile zebrafish. By exploring the structure-activity relationship, it was found that the sulfate content, fucose content and molecular weight of fucoidan were important factors affecting LJSF4 activity. The excellent protective effect of LJSF4 indicated its potential application as anti-oxidative reagent in functional food and cosmetic industries.