Isolation, purification and antioxidant activities of polysaccharides from Grifola frondosa

► The water-insoluble polysaccharides were isolated from Grifola frondosa. ► Three main fractions were purified from the G. frondosa polysaccharides. ► Different in vitro assay systems were used. ► The G. frondosa polysaccharides have effective antioxidant activities. ► I helpful for the comprehensive utilization of G. frondosa resources.