A novel fraction of polysaccharides EP80 was prepared from Epimedium sagittatum by grading-alcohol precipitation.Physicochemical properties of fraction EP80 were analyzed by different techniques such as thin-layer chromatography and thermogravimetric analysis.Structural characteristics of fraction EP80 were studied by various methods such as Fourier transform infrared spectroscopy,circular dichroism,Congo red experiment and scanning electron microscopy.Besides,in vitro antioxidant activity and effects of fraction EP80 on two enzymes related to alcohol metabolism were investigated.The results indicate that fraction EP80 with triple helix structure has a pyranose-ring skeleton.And its molecular weight was 3.2×104 Da,which was composed of galactose,arabinose,glucose and xylose.There are a positive Cotton effect near 230 nm and a negative Cotton effect near 260 nm.The micromorphology of fraction EP80 is irregular flakes with prominent fold structure.Fraction EP80 thermally loses weight at the range of 240-350 ℃.The effective concentrations (EC50) that scavenge DPPH and ABTS radicals by 50% are 0.029 and 0.235 mg/mL,respectively.Fraction EP80 obviously activates alcohol dehydrogenase and acetaldehyde dehydrogenase,and its EC₅₀ on acetaldehyde dehydrogenase is significantly lower than that on alcohol dehydrogenase (P＜0.01).These results are helpful to exploitation and utilization of novel fractions of E. sagittatum polysaccharides.

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