Azamollugin, a mollugin derivative, has inhibitory activity on MyD88- and TRIF-dependent pathways

Previously, we reported that azamollugin, an aza-derivative of mollugin, exhibited potent inhibitory activity on NO production in LPS-stimulated RAW 264.7 cells. Further investigations in this study revealed that azamollugin not only suppressed iNOS gene expression regulated by NF-κB, but also inhibited LPS-induced IFN-β expression, which is known to be regulated by IRF3. Azamollugin exhibited an inhibitory activity on LPS-induced IRAK1 activation, suggesting inhibitory effect on the MyD88-dependent pathway. Furthermore, azamollugin inhibited LPS-induced phosphorylation of IRF3 and its upstream factor, TBK1/IKKε, suggesting an inhibitory effect on the TRIF-dependent pathway via TLR4. In addition, azamollugin also suppressed poly(I:C)-induced phosphorylation of TBK1 and IRF3, suggesting an inhibitory effect on the TRIF-dependent pathway via TLR3. These results suggest that azamollugin has inhibitory activity against both the MyD88-dependent and TRIF-dependent pathways, respectively.