Effects of fucoidan on normal and xenograft zebrafish in vivo. (A) Toxicological analysis of fucoidan (0, 100, 200, and 300 μg/mL) was performed using fucoidan-exposed zebrafish larvae for 48 h to evaluate toxicity, cardiotoxicity, development, and kinesis in vivo. Scale bar indicates 250 µm. (B) Apoptotic effects of fucoidan on zebrafish larvae was analyzed using acridine orange to detect apoptotic cells after 48 h incubation. (C–F) Expression of apoptosis-related genes was estimated in fucoidan-treated zebrafish larvae for 48 h by quantitative RT-PCR. The scale bar indicates 50 µm. (G,F) In zebrafish xenograft model generated with microinjection of ES-2 (G) and OV-90 (H) cells, pre-treated fucoidan gradually inhibited tumor formation leading to a decrease in tumor size in vivo. The scale bar reveals 25 μm in square panels and 100 μm in rectangle panels. *** p < 0.001, ** p < 0.01, and * p < 0.05 indicate significant effects of fucoidan.

Anti-angiogenic activity of fucoidan in vivo and in vitro. (A) Zebrafish fli1 Tg (eGFP) models were analyzed to visualize vascular development in response to fucoidan. Fucoidan disrupted vasculature development, especially dorsal longitudinal anastomotic vessel (DLAV), dorsal aorta (DA), and intersegmental vessels (ISVs). Scale bar indicates 300 μm in left panels and 60 μm in right magnified panels. (B–G) Expression of angiogenesis-related genes was validated in fucoidan-treated fli1 Tg zebrafish by quantitative RT-PCR analysis. (H–N) Reduction of angiogenesis-related genes in ES-2 and OV-90 cells with the combination of fucoidan and cisplatin or paclitaxel. Messenger RNA expression of target genes was calculated based on that of GAPDH gene. *** p < 0.001, ** p < 0.01, and * p < 0.05 indicate significant effects of each treatment compared with vehicle-treated control cells. # represents significances (p < 0.05) compared with fucoidan alone.