Phenolic Compounds Isolated from Psoralea corylifolia Inhibit IL-6-induced STAT3 Activation

Inhibiting interleukin-6 (IL-6) has been postulated as an effective therapy in the pathogenesis of several inflammatory diseases. In this study, seven flavonoids were isolated from the methanol ex-tracts of Psoralea corylifolia by bioactivity-guided fractionation. The structures of bakuchiol (1), bavachinin (2), neobavaisoflavone (3), corylifol A (4), corylin (5), isobavachalcon (6), and bavachin (7) were determined by spectroscopic analysis (H-1-, (CNMR)-C-13 and MS). We demonstrated that compounds 1-7 showed an inhibitory effect on IL-6-induced STAT3 promoter activity in Hep3B cells with IC50 values of 4.57 +/- 0.45, 3.02 +/- 0.53, 2.77 +/- 0.02, 0.81 +/- 0.15, 1.37 +/- 0.45, 2.45 +/- 0.13, and 4.89 +/- 0.05 mu m, respectively. These compounds also inhibited STAT3 phosphorylation induced by IL-6 in Hep3B cells. Overall, several flavonoids from P. corylifolia might be useful remedies for treating inflammatory diseases by inhibiting IL-6-induced STAT3 activation and phosphorylation.