Epimagnolin A inhibits IL-6 production by inhibiting p38/NF-κB and AP-1 signaling pathways in PMA-stimulated THP-1 cells

Epimagnolin A is a lignan obtained from the flower buds of Magnolia fargesii, which is traditionally used in Asian medicine for treating headache and nasal congestion. A herbal compound fargesin obtained from M. fargesii, has exerted anti-inflammatory effects in human monocytic THP-1 cells in the previous study. The anti-inflammatory effects of epimagnolin A, however, have been not elucidated yet. In this study, it was demonstrated that epimagnolin A reduced phorbol-12-myristate-13-acetate (PMA)-induced IL-6 promoter activity and IL-6 production in human monocytic THP-1 cells. Furthermore, it was investigated the modulating effects of epimagnolin A on mitogen-activated protein kinase, nuclear factor-kappa B (NF-kappa B), and activator protein 1 (AP-1) activities. Phosphorylation of p38 and nuclear translocation of p50 and c-Jun were down-regulated by epimagnolin A in the PMA-stimulated THP-1 cell. The results revealed that epimagnolin A attenuated the binding affinity of NF-kappa B and AP-1 transcription factors to IL-6 promoter and IL-6 production through p38/NF-kB and AP-1 signaling pathways in the PMA-stimulated THP-1 cells. These results suggest that epimagnolin A can be a useful drug for the treatment of inflammatory diseases.