Inhibitory effects of polyphenols toward HCV from the mangrove plant Excoecaria agallocha L.

Four new polyphenols namely excoecariphenols A-D (1-4) were isolated from the Chinese mangrove plant Excoecaria agallocha L. together with 23 known phenolic compounds. The structures of new compounds were elucidated on the basis of extensive spectroscopic analyses including IR, MS, NMR, and CD data. Excoecariphenols A and B presented as the unusual flavane-based 1-thioglycosides. Part of the isolated polyphenols were tested against hepatitis C NS3-4A protease and HCV RNA in huh 7.5 cells. Excoecariphenol D, corilagin, geraniin, and chebulagic acid showed potential inhibition toward HCV NS3-4A protease with IC50 values in a range of 3.45-9.03 μM, while excoecariphenol D and corilagin inhibited HCV RNA in huh 7.5 cells significantly. A primary structure-activity relationship (SAR) is discussed.