OBJECTIVE: Study on isolation of the lycium barbarum polysaccharide (LBP) and its effects on anti active oxygen free radical. METHODS: Isolation of LBP by hot water extracted and alcohol precipitation, and purified by absorbent with Polyerde column membrane and eluted with hot water; RESULTS: Scavenge rate to O 2 -· and OH · with the crude LBP were 58.6% and 49.7%,respectively; and with pure LBP were 40.7% and 31.4%, respectively; CONCLUSION: th...