Abstract: Tremella fuciformis Berk(TFB) is widely distributed in southwest China. Its sporocarps are used as traditional Chinese medicine for nourishing yin and promoting fluid production, moistening lung and relieving cough. In this study, a polysaccharide with the molecular weight of 58962, named TFBP-A, was isolated from the fermentation product of TFB by alkaline solution. Its antioxidant activity was evaluated using three in vitro assay experiments including hydroxyl free radicals scavenging, superoxide anion free radicals elimination and red cells hemolysis inhibition. TFBP-A showed scavenging activity to hydroxyl free radicals and the EC₅₀ was 0.191 mg·mL^-1; while it could also eliminate superoxide anion free radicals and the highest eliminating ratio was 53.0%; it could still inhibit red cells hemolysis aroused by H₂O₂ and the inhibition ratio was 78.6%. These results suggest that TFBP-A has certain antioxidant activity.

Key words: antioxidant activity, Tremella fuciformis Berk, Polysaccharide, Traditional Chinese medicine, purification