A citrus flavonoid, 6-demethoxytangeretin, suppresses production and gene expression of interleukin-6 in human mast cell-1 via anaplastic lymphoma kinase and mitogen-activated protein kinase pathways

Citrus species has been traditionally used in Korea for the treatment of coughing, sputum and dyspepsia. Of the known citrus flavonoids, 6-demethoxytangeretin was reported to exert anti-inflammatory activity. In order to determine the anti-allergic activity of 6-demethoxytangeretin, we examined whether or not 6-demethoxytangeretin was able to suppress activation of the human mast cell line, HMC-1, induced by phorbol 12-myristate 13-acetate (PMA) plus A23187. Interleukin-6 production and relevant gene expression in activated HMC-1 cells were determined by enzyme-linked immunosorbent assay (ELISA) and quantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis. Also, the involvement of the anaplastic lymphoma kinase (ALK) and mitogen-activated protein kinases (MAPKs) in activated HMC-1 cells were studied. 6-Demethoxytangeretin suppresses interleukin-6 production, tumor necrosis factor-alpha gene expression, ALK and MAPKs in HMC-1 cells stimulated by PMA plus A23187. Therefore, it was evident that 6-demethoxytangeretin suppressed activation of HMC-1 cells by PMA plus A23187 by inhibiting the activity of ALK and MAPKs and subsequently suppressing gene expression, which suggest that 6-demethoxytangeretin may be involved in the regulation of mast cell-mediated inflammatory responses.