In Vitro Free Radical and ONOO- Scavengers from Sophora flavescens

Activity-guided fractionation of the CH2CI2-soluble fraction of the roots of Sophora flavescens furnished five 1,1 -diphenyl-2-picrylhydrazyl (DPPH) free radical scavengers: trans-hexadecyl ferulic acid (1), cis-octadecyl ferulic acid (2), trans-hexadecyl sinapic acid (3), (-)-4-hydroxy-3-methoxy-(6aR,11aR)-8,9-methylenedioxypterocarpan (4) and desmethylanhydroicaritin (8), along with nine known inactive compounds: (-)-maackiain (5), xanthohumol (6), formononetin (7), (2S)-2’-methoxykurarinone (9), (2S)-3β,7,4’-trihydroxy-5-methoxy-8-(γ,γ-dimethylallyl)-flavanone (10), (2S)-7,4’-dihydroxy-5-methoxy-8-(γ,γ-dimethylallyl)-flavanone (11), umbelliferone (12), kuraridin (13), and trifolirhizin (14). Compounds 1-4 and 8 exhibited DPPH free radical scavenging effects at IC50 values of 33.01 ± 0.20, 57.06 ±0.16, 39.84 ± 0.36, 35.83 ± 0.47, and 18.11 ± 0.04 ¼M, respectively. L-Ascorbic acid, when used as a positive control, exhibited an IC50 value of 7.39 ± 0.01 ¼M. Compounds 1-4 and 8 also appeared to exert significant scavenging effects on authentic ONOO-, with IC50 values of 5.76 ± 1.19, 15.06 ± 1.64, 8.17 ±4.97, 1.95 ± 0.29, and 4.06 ± 2.41 ¼M, respectively. Penicillamine (IC50= 2.36 ± 0.79 μM) was used as a positive control. In addition, compounds 2, 4, 6, 8, and 10 were isolated from this plant for the first time.