A glucan is a polysaccharide derived from D-glucose, linked by glycosidic bonds. Beta-glucans, such as laminarin, are important energy reserve polysaccharides in macroalgae, constituting up to 35% of the dried weight of the macroalgal biomass in several brown seaweed. Many beta-glucans are medically important, showing antiinflammatory, immunostimulatory, antioxidant, anticoagulant, antiviral, antiproliferative, antiapoptosis and antitumour properties. They represent a drug target for antifungal medications of the echinocandin class. A glucan is a polysaccharide derived from D-glucose, linked by glycosidic bonds. Beta-glucans, such as laminarin, are important energy reserve polysaccharides in macroalgae, constituting up to 35% of the dried weight of the macroalgal biomass in several brown seaweed. Many beta-glucans are medically important, showing antiinflammatory, immunostimulatory, antioxidant, anticoagulant, antiviral, antiproliferative, antiapoptosis and antitumour properties. They represent a drug target for antifungal medications of the echinocandin class. The following are glucans:(The α- and β- and numbers clarify the type of O-glycosidic bond.)