Potential Antiviral Lignans from the Roots of Saururus chinensis with Activity against Epstein-Barr Virus Lytic Replication

Epstein-Barr virus (EBV) is a member of the gamma-herpes virus subfamily and has been implicated in the pathogenesis of several human malignancies. Bioassay-guided fractionation was conducted on an EtOAc-soluble extract of the roots of Saururus chinensis and monitored using an EBV lytic replication assay. This led to the isolation of 19 new (1-19) and nine known (20-28) lignans. The absolute configurations of the new lignans were established by Mosher's ester, ECD, and computational methods. Eight lignans, including three sesquineolignans (19, 23, and 24) and five dineolignans (3, 4, 26, 27, and 28), exhibited inhibitory effects toward EBV lytic replication with EC50 values from 1.09 to 7.55 mu M and SI values from 3.3 to 116.4. In particular, manassantin B (27) exhibited the most promising inhibition, with an EC50 of 1.72 mu M, low cytotoxicity, CC50 > 200 mu M, and SI > 116.4. This is the first study demonstrating that lignans possess anti-EBV lytic replication activity.