The effect of seasonality and geographic location on sulphated polysaccharides from brown algae

Fucoidans, a diverse group of sulphated polysaccharides from brown algae, are biopolymers with many documented activities in vitro. While several factors are known to influence these activities, the degree of sulphation of the polymer is often regarded as a key parameter. The degree of sulphation on a biopolymer may be seasonally dependent, which, in turn, may affect the bioactivities of fucoidans. In this study, the effect of season and geographical location on the fucoidan sulphur content (as a proxy for degree of sulphation), was investigated. Crude fucoidan extracts were obtained using microwave-assisted extraction on eight different brown algae species, which were then analysed using elemental analysis. A significant seasonal dependence on the sulphur content in fucoidan extracts from Fucus serratus was observed. The difference in sulphur content between the investigated Fucus species is likely due to their different reproduction strategies. Of the eight species used in this study, Ascophyllum nodosum and Fucus evanescens contained the most sulphated fucoidans, while the species Dictyosiphon foeniculaceus contained lightly sulphated fucoidans. This suggests that species which thrive in saline waters may contain more sulphated fucoidans as a means of mitigating osmotic stress. No significant effects on the sulphur content in fucoidans from Fucus vesiculosus was observed between the three investigated countries. From these findings, it is apparent that seasonality is an important parameter, which must be considered for large scale production of highly sulphated fucoidans.