Suppression of RelA/p65 Transactivation Activity by a Lignoid Manassantin isolated from Saururus chinensis

In our search for NF-kB inhibitors from natural resources, we have previously identified two structurally related dilignans, manassantin A and B as specific inhibitors of NF-kB activation from Saururus chinensis. However, their molecular mechanism of action remains unclear. We here demonstrate that manassantin A and B are potent inhibitors of NF-kB activation by the suppression of transciptional activity of RelA/p65 subunit of NF-kB. These compounds significantly inhibited the induced expression of NF-kB reporter gene by LPS or TNF-a in a dose-dependent manner. (omitted)