Study of phenolic-polysaccharide interactions in brown seaweed

Brown seaweed has a rich source of bioactives, notably antioxidative phenolic compounds and sulphated polysaccharides. Despite their importance, the interactions between these compounds and their resultant antioxidant activities have not been extensively studied. This research aims to investigate the interaction between seaweed-derived phenolics and polysaccharides in terms of their antioxidant activity, exploring their potential interactions through in silico molecular docking, and validating them using Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) and differential scanning calorimetry (DSC). Reduced antioxidant activities were observed in the seaweed-derived phenolics and polysaccharides combination. The in silico molecular docking studies and experimental analyses revealed non-covalent interactions, mainly driven by hydrogen bonding between fucoidan and catechin or phloroglucinol. The resulting 'complex' formation varied in size and thermodynamic stability, suggesting structure-dependent interactions between fucoidan and phenolic compounds. This research helps to understand the marine phenolic-polysaccharide interaction, contributing to their effective application in the functional food and nutraceutical industries.