Sanggenon C and O inhibit NO production, iNOS expression and NF-κB activation in LPS-induced RAW264.7 cells

OBJECTIVE: The NO production through the iNOS induction by activation of nuclear factor (NF-κB) is known to involve in various inflammatory conditions. Sanggenon C and O, two Diels-Alder type adducts isolated from Morus alba, a plant has been used for the anti-inflammatory purpose in the Oriental medicine, were investigated for their effect on the NO production, iNOS expression and NF-κB activity. METHODS: The inhibitory effects of sanggenon C and O on the NF-κB activity were investigated in LPS-stimulated RAW264.7 cells by SEAP reporter assay. The regulation of the iNOS expression and IκBα activation by two compounds was also evaluated by Western blot. RESULTS: Both compounds strongly inhibited NO production and NF-κB activation in a dose-dependent manner. The expression of the iNOS protein was also suppressed by treatment of the compounds (10 and 1 µM). Sanggenon O showed stronger inhibition than the diastereomer sanggenon C. Both compounds prevented the phosphorylation and degradation of IκBα protein. CONCLUSION: We demonstrated that sanggenon C and O inhibited NO production and iNOS expression by suppressing NF-κB activity and IκBα activation.