Homoisoflavones as the antioxidants responsible from bulbs of Scilla scilloides

Scilla scilloides Druce has been used as a folk medicine to treat dermal inflammation; however, the medicinal property of this plant remains to be entirely clarified. The ethyl acetate extract prepared from bulbs of S. scilloides exhibited antioxidative activities on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, hydrogen peroxide (H2O2) and nitric oxide (NO) scavenging assays. Nine homoisoflavones (1–9) yielded from this extract were further examined for their antioxidative activities. Among these chemicals tested, five homoisoflavones (1–3, 5 and 7), six homoisoflavones (1–3 and 5–7) and two homoisoflavones (4 and 5) resulted in showing higher activities than the others in DPPH radical, H2O2 and NO scavenging assays, respectively. Calculated EC50 values indicate 3 as the strongest in the DPPH radical scavenging analysis. These results may indicate a potential role of S. scilloides for its medicinal use and homoisoflavones as the antioxidants responsible.