Seaweed-derived polysaccharides as antibacterial and antiviral ingredients

In recent years, seaweed-derived polysaccharides have emerged as a novel class of bioactive ingredients. These polysaccharides include the red seaweed polysaccharides carrageenan, agar, agarose and porphyran, the brown seaweed polysaccharides fucoidan, laminarin and alginate and the green seaweed polysaccharide, ulvan. These polysaccharides present as diverse, complex structures due to their sulfation patterns, glycosidic linkages and monosaccharide content. The wide range of structures allow diverse bioactivities, including a broad spectrum of antibacterial, antiviral, immunomodulatory and prebiotic activities. This review describes the structures of these polysaccharides, their reported in vitro and in vivo antimicrobial activities, and the mechanisms underlying these activities. In addition, the extraction and commercial use of these polysaccharides are discussed. By highlighting the broad range of beneficial activities associated with these polysaccharides, this review aims to demonstrate the potential of seaweed polysaccharides as functional ingredients for preventing infection and improving human health.