Fucoidan, the complex fucose-containing sulphated polysaccharide varies considerably in structure, composition, and bioactivity, depending on the source, species, seasonality, and extraction method. In this study, we examined five fucoidans extracted from the same seaweed species Undaria pinnatifida but from different geological locations, and compared them to the laboratory-grade fucoidan from Sigma (S). The five products differed in molecular composition. The amount of over 2 kDa low molecular weight fraction (LMWF) of the New Zealand crude fucoidan (S1) was larger than that of S, and this fraction was unique, compared to the other four fucoidans. The difference of molecular compositions between S and S1 explained our previous observation that S1 exhibited different anticancer profile in some cancer cell lines, compared with S. Since we observed this unique LMWF, we compared the cytotoxic effects of a LMWF and a high molecular weight fucoidan (HMWF) in two breast cancer cell lines—MCF-7 and MDA-MB-231. Results indicated that the molecular weight is a critical factor in determining the anti-cancer potential of fucoidan, from the New Zealand U. pinnatifida, as the LMWF exhibited a dose-dependent inhibition on the proliferation of breast cancer cells, significantly better than the HMWF, in both cell lines. A time-dependent inhibition was only observed in the MCF-7. Induction of caspase-dependent apoptosis was observed in the MDA-MB-231 cells, through the intrinsic apoptosis pathway alone, or with the extrinsic pathway. LMWF stimulated a dose-dependent NOS activation in the MDA-MB-231 cells. In conclusion, the fucoidan extracted from the New Zealand U. pinnatifida contains a unique LMWF, which could effectively inhibit the growth of breast cancer cell lines. Therefore, the LMWF from New Zealand U. pinnatifida could be used as a supplement cancer treatment.

AbstractThe commercial landscape of seaweed use in New Zealand (NZ) has shifted and evolved since it was last reviewed in 2006. One of the largest changes saw the introduction of Macrocystis pyrifera and green-lipped mussel spat (which is landed attached to beach-cast seaweed) into the Quota Management System—the primary tool for commercial fisheries management in NZ. There have also been policy changes around commercial harvesting and farming of Undaria pinnatifida, an introduced brown alga native to Asia. Traditionally, commercial algal utilization has been limited to agar production and beach-cast collection for aquaculture feeds, though demand for seaweed products has increased with a growing Asian population in NZ. The NZ seaweed industry is at an early developmental stage, but it has the potential to offer high quality seaweed stock and value-added products to the world market. The exploration of seaweed farming, the growing demand for seaweed fertilizers and the development of high-value bioactive products such as fucoidan has attracted interest from marine farmers and entrepreneurs. The key to success for the NZ seaweed industry rests in developing high-value products for an export market, from integrated farming, harvesting and processing that can deliver the most value, consume the least energy and generate minimal waste.