In vitro free radical and ONOO- scavengers from Sophora flavescens.

Activity-guided fractionation of the CH2Cl2-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)-3beta,7,4'-trihydroxy-5-methoxy-8-(gamma,gamma-dimethylallyl)-flavanone (10), (2S)-7,4'-dihydroxy-5-methoxy-8-(gamma,gamma-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 microM, respectively. L-Ascorbic acid, when used as a positive control, exhibited an IC50 value of 7.39 +/- 0.01 microM. 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 microM, respectively. Penicillamine (IC50 = 2.36 +/- 0.79 microM) was used as a positive control. In addition, compounds 2, 4, 6, 8, and 10 were isolated from this plant for the first time.