Cannabisin A was isolated from the crude lignanamides extract of Fructus Cannabis of Bama by chloroform-methanol (85∶ 15) with silica gel column chromatography, and identified by FAB-MS, NMR.Researching the scavenging activity of the crude lignanamides extract, the purified lignanamides extract by macroporous resin and cannabisin A by three diffierent free radical systems such as 1, 1-Diphenyl-2-picryl-hydrazyl free radical (DPPH(.)), superoxide anion free radical (O2-), hydroxide free radical (OH(.)).The results showed that both of them h...