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Three undescribed diarylheptanoids (3: -5: ) and six known curcuminoids (1, 2: , and 6: -9: ) were obtained from the ethyl acetate-soluble fraction of an ethanolic extract of Curcuma phaeocaulis . Their chemical structures and absolute configurations were elucidated by high-resolution electrospray ionization mass spectrometry, nuclear magnetic resonance spectroscopy, circular dichroism spectroscopy, and the modified Mosher's method. Previous studies constructed Hep3B cells stably transfected with pSTAT3-Luc plasmid containing STAT3 binding site to discover STAT3 inhibitors from natural products. The STAT3 inhibitory activities of all isolates were measured in transfected Hep3B cells after treatment with IL-6. Compound 5: ((5 R )-1,7-Bis(3,4-dimethoxyphenyl)-3-methoxy-1-hepten-5-ol), demethoxycurcumin (7: ), and curcumin (8: ) exhibited significant inhibitory activity (IC 50 values: 11.1, 1.9, and 1.6 µM, respectively). Furthermore, IL-6-induced phosphorylation of STAT3, and the mRNA expression levels of inflammation-related genes such as CRP, IL-1β, ICAM-1, and SOCS3 were significantly reduced by exposure to compound 5: . These data suggested that the inhibitory activity of 5: is associated with the suppression of STAT3 phosphorylation. Thus, compound 5: may be a promising candidate for the treatment of cancer or inflammatory diseases related to the IL-6/STAT3 signaling pathway., Competing Interests: The authors declare no conflicts of interest., (Georg Thieme Verlag KG Stuttgart · New York.)

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 extracts 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 (1H-, 13C- NMR 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 µΜ, 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., (Georg Thieme Verlag KG Stuttgart · New York.)