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 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.