Objective: To determine the content of polysaccharides in Laggera pterodonta and investigate its in vitro antioxidative activity. Method: Polysaccharides in L. pterodonta was extracted by ultrasonic-microwave synergistic method

the content of polysaccharides was determined by phenol-sulfuric acid colorimetry

its antioxidant activity was measured by FRAP assay

salicylic acid assay

ABTS assay and adjacent benzene pyrogallol assay. Result: The content of polysaccharides in L. pterodonta was 200 mg·g-1.Compared with the positive control of ascorbic acid and tea polyphenols

reducing Fe3+ antioxidant capacity of polysaccharides in L. Pterodonta (829.75 μmol·g-1) was weaker than ascorbic acid (1 536.5 μmol·g-1)

but higher than tea polyphenols (739.75 μmol·g-1).Scavenging ABTS+radical capacity (IC50 0.197 g·L-1) and superoxide anion radical capacity (IC50 0.289 g·L-1) was lower than ascorbic acid (IC50 were 0.032

0.259 g·L-1

respectively)

but higher than tea polyphenols (IC50 were 0.233

0.335 g·L-1

respectively).Scavenging OH·(IC50 0.245 g·L-1)was lower than ascorbic acid (IC50 0.199 g·L-1) and tea polyphenols (IC50 0.233 g·L-1). Conclusion: Phenol-sulfuric acid colorimetry to determine the content of polysaccharides from L. pterodonta was simple

rapid and accurate with good sensitivity

antioxidant activity of polysaccharides from L. pterodonta was strong.