Structure characterization and antioxidant activity of fucoidan isolated from Undaria pinnatifida grown in New Zealand.

Fucoidan from brown seaweed species, Undaria pinnatifida, has numerous bioactive properties such as antioxidant and anticancer activities. The objective of this research was to quantify the chemical composition of fucoidan isolated from U. pinnatifida harvested in New Zealand and to determine its molecular structure and antioxidant capacity. Crude fucoidan (Fcrude) and purified fucoidan with molecular weight cut off (MWCO) of 300 kDa (F300) were compared against a fucoidan standard (FStd). FStd contained significantly higher sulfate content as compared to Fcrude and F300. Based on FTIR and 2D HSQC analysis, it was proposed that the purified fucoidan was composed of an alternating fucose-galactose backbone linked together via 1,3 glycosidic bonds with sulfation at C2 and C4 positions. Fucoidan samples from New Zealand exhibited secondary antioxidant capacity close to that of butylated hydroxyanisole (BHA), with low-molecular-weight fucoidan had significantly higher capacity than that of BHA.