Anti-influenza A virus effects of fructan from Welsh onion (Allium fistulosum L.)

► We isolated a fructan from Allium fistulosum as an anti-influenza A virus polysaccharide. ► Structural analyses revealed the fructan was an inulin-type polysaccharide. ► The polysaccharide possessed anti-influenza A virus activity in animal model. ► The fructan showed immunomodulatory effects in vitro.