Abstract
Background/Aim: Fucoidans are gaining popularity as natural immunomodulators. The aim of this study was to compare the immunological activities or both purified samples and commercially available mixtures containing fucoidan. Materials and Methods: We evaluated the effects of various samples on phagocytosis, mitogenic response, natural killer (NK) activity, antibody formation and inhibition of breast cancer growth. Results: We found significant immunostimulating activity, but the strength of these effects was different among individual samples. Conclusion: Fucoidans have strong immunostimulating potential, including inhibition of cancer, with isolated samples offering better activity than commercial mixtures.
Fucoidan is a complex sulfated polysaccharide consisting of sulfated fucose residues and found mostly in brown marine algae, echinoderms (1) and seagrasses (2). Fucoidans exhibit numerous biological activities found both in in vitro and in vivoexperiments. Fucoidan extracts have been found to ameliorate acute colitis (3), have anticancer activity (4) mediate via natural killer (NK) cells (5) and affect inflammation, vascular physiology, as well as oxidative stress (6, 7). Some effects differ based on the type of extract, as documented by the differential effects of high and low molecular weight fucoidans on the severity of arthritis in mice. The low molecular weight samples reduced arthritis via suppression of Th1-mediated immunity, whereas high molecular weight samples enhanced the inflammatory activation of macrophages (8). Subsequent experiments revealed that high molecular weight fucoidans stimulated spleen cells, whereas low molecular weight samples had little activity or were toxic (9). The reasons for these differences are still unknown. Using a fish model, however, dietary fucoidan was found to influence blood chemistry and constituents, antioxidation and innate immunity (10). In human models, fucoidan delayed apoptosis and induced proinflammatory cytokines, probably via activation of the PI3K/AKT pathway (11). As fucoidan can function as an adjuvant and stimulate antibody response (12), it has been used to improve vaccine efficacy (13).
Cancer development is the most studied effect of fucoidan. The mechanisms are still unknown. However, fucoidan can directly induce cytotoxicity and apoptosis of cancer cells (14) probably explained by an additional study suggesting implication of macrophages and blood leukocytes in relation to fucoidan (15).
In our study, we not only directly compared the biological activities of individual fucoidan samples, but also compared purified samples with commercially available component mixtures. Thus, our study answers the question not only whether fucoidans influence immune reactions, but also if the popular idea of combining biologically active molecules together improves their effectiveness.