Anti-hepatitis B virus lignans from the root of Streblus asper

Four new lignans, strebluslignanol F (1), (7'R,8'S,7″R,8″S)-erythro-strebluslignanol G (2), isomagnaldehyde (3) and isostrebluslignanaldehyde (4), along with 12 known lignans (5-16) were isolated from the ethyl acetate-soluble part of MeOH extract of the root of Streblus asper. Their structures were elucidated through various spectroscopic methods, including 1D NMR ((1)H NMR, (13)C NMR), 2D NMR (HMQC, HMBC and NOESY) and HRMS. The stereochemistry at the chiral centers was determined using CD spectra, as well as analyses of coupling constants and optical rotation data. The isolated lignans were evaluated for their anti-HBV activities in vitro using the HBV transfected HepG2.2.15 cell line. The most active lignans, (7'R,8'S,7″R,8″S)-erythro-strebluslignanol G, magnolol, isomagnolol and isolariciresinol, exhibited significant anti-HBV activities with IC50 values of 1.58, 2.03, 10.34 and 3.67 μM, respectively, for HBsAg with no cytotoxicity, and of 3.24, 3.76, 8.83 and 14.67 μM, respectively, for HBeAg with no cytotoxicity. (7'R,8'S,7″R,8″S)-erythro-Strebluslignanol G and magnolol showed significant anti-HBV activities to inhibit the replication of HBV DNA with the IC50 values of 9.02 and 8.67 μM, respectively.