Fucoidan is a sulfated polysaccharide found in brown seaweed. Due to its reported biological activities, including antiviral, antibacterial and anti-inflammatory activities, it has garnered significant attention for potential biomedical applications. However, the direct relationship between fucoidan extracts’ chemical structures and bioactivities is unclear, making it extremely challenging to predict whether an extract will possess a given bioactivity. This relationship is further complicated by a lack of uniformity in the recent literature in terms of the assessment and reporting of extract properties, yield and chemical composition (e.g., sulfate, fucose, uronic acid and monosaccharide contents). These inconsistencies pose significant challenges when directly comparing extraction techniques across studies. This review collected data on extract contents and properties from a selection of available studies. Where information was unavailable directly, efforts were made to extrapolate data. This approach enabled a comprehensive examination of the correlation between extraction techniques and the characteristics of the resulting extracts. A holistic framework is presented for the selection of fucoidan extraction methods, outlining key heuristics to consider when capturing the broader context of a seaweed bioprocess. Future work should focus on developing knowledge within these heuristic categories, such as the creation of technoeconomic models of each extraction process. This framework should allow for a robust extraction selection process that integrates process scale, cost and constraints into decision making. Key quality attributes for biologically active fucoidan are proposed, and areas for future research are identified, such as studies for specific bioactivities aimed at elucidating fucoidan’s mechanism of action. This review also sets out future work required to standardize the reporting of fucoidan extract data. Standardization could positively enhance the quality and depth of data on fucoidan extracts, enabling the relationships between physical, chemical and bioactive properties to be identified. Recommendations on best practices for the production of high-quality fucoidan with desirable yield, characteristics and bioactivity are highlighted.

Fucoidan is a sulfated polysaccharide derived from brown seaweed, reported to possess diverse biological activities that make it a molecule of great interest for nutraceutical and biomedical applications. A significant challenge to its wider implementation is a lack of understanding of the relationship between fucoidan’s structural and chemical characteristics with its biological activity. So far, approaches to identifying these relationships have been limited to qualitative comparisons of chemical and biological datasets or through chemically modified fucoidans. This work aimed to apply a formal methodology to elucidate potential relationships worthy of further exploration. The biological activity of commercial fucoidan extracts was assessed after detailed chemical characterization. The extracts exhibited multiple bioactivities, notably antioxidant activity, antiviral activity against Nipah virus, antifungal activity against Candida dubliensis and prebiotic effects on Lactobacillus casei, with no antifungal activity against Candida albicans, Candida auris and Cryptococcus neoformans, nor antibacterial effects against Klebsiella pneumoniae. Correlation analysis of biological activity and extract chemical characterization data identified several potential key quality attributes. Other than high fucose content, high sulfate content is identified as potentially important for antioxidant, antiviral, antifungal, and prebiotic activities. This work addressed the literature’s debate regarding the optimal molecular weight for bioactivity, suggesting that it depends on the specific microbe to which a fucoidan extract is applied. This study demonstrated that a formalized comparative approach, linking chemical and structural data with biological activity, can effectively identify important characteristics of fucoidan for a specific bioactivity. Future work will focus on expanding this approach by assessing the bioactivity of a wider array of chemically characterized fucoidan extracts. Additionally, extracts possessing identified quality attributes should be produced and employed in mechanistic bioactive studies to further validate the correlations drawn in this work.

Fucoidan is a sulfated polysaccharide derived from brown seaweed, reported to possess diverse biological activities that make it a molecule of great interest for nutraceutical and biomedical applications. A significant challenge to its wider implementation is a lack of understanding of the relationship between fucoidan’s structural and chemical characteristics with biological activity. So far, approaches to identifying these relationships have been limited to qualitative comparisons of chemical and biological datasets or producing unnatural modified fucoidans through chemical methods. This work aimed to apply a formalized methodology to elucidate potential relationships worthy of further exploration. The biological activity of commercial fucoidan extracts that had undergone a detailed chemical characterization process was assessed. The extracts exhibited multiple bioactivities, notably antioxidant activity, antiviral activity against Nipah virus, antifungal activity against Candida dubliensis and prebiotic effects on Lactobacillus casei. With no antifungal activity against Candida albicans, Candida auris and Cryptococcus neoformans, nor antibacterial effects against Klebsiella pneumoniae. Correlation analysis of biological activity and extract chemical characterization data identified several potential key quality attributes. With high fucose content, high sulphate content identified as potentially important for antioxidant, antiviral, antifungal, and prebiotic activities. This work addressed literature’s debate regarding the optimal molecular weight for bioactivity, suggesting that it depends on the specific microbe to which a fucoidan extract is applied.This study demonstrated that a formalized comparative approach, linking chemical and structural data with biological activity, can effectively identify important characteristics of fucoidan for a specific bioactivity that requires further exploration. Future work should focus on expanding this approach, measuring the bioactivity of more chemically characterized fucoidans against more microbes. Additionally, extracts possessing identified quality attributes should be produced and employed in mechanistic studies to further validate the correlations drawn in this work.