Neutral polysaccharides are composed of neutral monosaccharides such as glucose and xylose linked by glycosidic bonds and are polymerized as macromolecules in the range of thousands to millions. They are known to exhibit various properties depending on the type of composed monosaccharides, the bonding position, the presence / absence of side chains / branches, and so on. Since these polysaccharides have many hydroxyl groups (OH), they show affinity for water molecules. they act as hydrophilic colloids holding a large number of water molecules due to their properties. For industrial use, they are widely used for various purposes such as dispersion stabilization, suspension stabilization, viscosity imparting, gel-forming ability, film-forming feature, and adhesive effect.¹⁾

Acidic polysaccharides contain a lot of uronic acids (a compound in which the terminal hydroxy group [-CH₂OH] of aldohexose is oxidized to a carboxy group [-COOH]) and several sulfate groups (a compound in which the hydroxy group [-OH] of aldohexose is dehydrated condensation with sulfuric acid). These polysaccharides are thought to function with mechanisms that maintain the structure of plant tissues and protect them from exogenous substances. Polyuronic acid-containing pectin and gum arabic are found in land plants while polyuronic acid-containing alginic acid, sulfate group-containing carrageenan and fucoidan are obtained from seaweeds. For practical use, they are widely used for purposes such as imparting viscosity, adhesive effect, dispersion stabilization, aggregation suppression, protein stabilization, and gel-forming ability.²⁾

Glycosaminoglycans (GAGs) are long linear polysaccharides that form repeating disaccharide structures and have long been studied as systematic names for mucopolysaccharides. It is well known that it functions as a molecule of the extracellular matrix to support tissues present throughout the body. Due to their negative charge and binding to bioactive molecules, GAGs are intimately involved in the regulation of many cellular functions. In vivo, hyaluronic acid (HA) generally exists as a free sugar chain, but chondroitin sulfate (CS), dermatan sulfate (DS), keratan sulfate (KS), and heparan sulfate (HS) have sulfate group modifications in their internal structures, bind to coreproteins as side chains varying lengths. GAG-modified protein molecules are called proteoglycans (PG).³⁾

Sulfated polysaccharides are known as multifunctional polysaccharides, that are related in physiological functions on the cell surface in vivo. These polysaccharides have supportive effects of viral infections. It has been reported that chemical mimics of sulfated polysaccharides inhibit viral adhesion during infection step.⁴⁾