In vitro antioxidant activities of water-soluble polysaccharides extracted from Isaria farinosa B05

The water-soluble exo-polysaccharides (WSEPS) and intrapolysaccharides (WSIPS) were prepared from the fermentation broth and mycelia of Isaria farinosa B05, respectively, and their antioxidant activities in vitro were studied by various antioxidant assays, including hydroxyl radical scavenging, superoxide radical scavenging, hydrogen peroxide (H2O2) scavenging, metal chelating activities, reducing power and antilipid peroxidation. The results show that the water-soluble polysaccharides extracted from I. farinosa B05 had a high antioxidant activity in a concentration-dependent manner (except the activity of antilipid peroxidation). WSIPS quenched hydroxyl radicals at high amounts but not at low amounts; WSEPS did not scavenge hydroxyl radicals. WSEPS and WSIPS had a similar activity in scavenging superoxide radicals. WSIPS had a slightly higher H2O2-scavenging activity than WSEPS before the activity reached 100% at the amount of 10.24 mg. Similar to the result of hydroxyl radical scavenging, WSIPS, but not WSEPS, chelated Fe2+. The reductive ability of WSEPS and WSIPS was similar and significant compared with the control at the range of 0.8-6.4 mg. Both WSEPS and WSIPS showed higher antilipid peroxidation activities at low amounts (<= 0.64 mg) than at high amounts. These results indicate that WSEPS and WSIPS had strong antioxidant activities and can be explored as novel potential antioxidants.