Abstract: Crude polysaccharides(CP)were obtained from Ophiopogon japonicus(Thumb.)Ker-Gawl by ultrasonic extraction, followed by trichloracetic acid deproteination and ethanol precipitation. CP were further purified by DEAE-sepharose fast-flow ion-exchange column chromatography. Finally the spectroscopy of CP was analyzed and the free radical scavenging activities of various fractions toward DPPH· and ·OH were studied. One neutral polysaccharide(NP)and three kinds of acidic polysaccharides(AP) were separated by DEAE-sepharose FF. The result showed that NP has very low activities in scavenging DPPH· and ·OH. The ability of three kinds of AP for scavenging DPPH· and ·OH were in the sequence of: AP3＞AP2＞AP1. AP3 has high ability of scavenging ·OH. CP has very high ability of scavenging DPPH· , and its ability of scavenging ·OH changed rapidly with the concentration change. The IC₅₀ of various polysaccharides toward DPPH· were: AP1 22.30g/L,AP2 9.96g/L,AP3 7.70g/ L; CP 2.01g/L. The IC₅₀ of various polysaccharides toward ·OH were: AP1 8.42g/L,AP2 5.73g/L,AP3 1.86g/ L; CP 4.93g/L.

Key words: Ophiopogons japonicus(Thumb.)Ker-Gawl, polysaccharides, extraction and purification, free radical scavenging activity