Structures and antiviral activities of polysaccharides from Sargassum trichophyllum

Isolation and characterization of polysaccharides from Sargassum trichophyllum, a type of brown algae, were performed. Three polysaccharides, ST-L, -A and -F were obtained and characterized as laminaran, alginate and fucoidan, respectively. ST-L was found to be a β-glucan consisting of terminal- (14.5 mol%), 1,3- (69.4%), 1,6- (33.4%), and 1,3,6-linked (12.8%) residues. ST-A was found to be a mannuronic acid-rich alginate (M/G = 1.88). ST-F consisted of fucose (79.1 mol%) and galactose (19.9 mol%), and its sulfate content was estimated to be 25.5%. Methylation analysis revealed that ST-F was mainly composed of terminal, 1,4- and 1,3-linked fucose and terminal, 1,2- and 1,6-linked galactose residues. Among these polysaccharides, only ST-F showed antiviral activity against herpes simplex virus type 2.