Structure-Function Correlations of Commercial Fucoidan Extracts: Antioxidant, Antiviral, Antifungal, Antibacterial and Prebiotic Activities.

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.