Anti-hepatitis B virus constituents from the stem bark of Streblus asper

The structures and absolute stereochemistries of seven neolignans including compounds (1–4) isolated from stem bark of Streblus asper have been determined by detailed spectroscopic analyses. The anti-HBV activity assays of the isolated compounds indicated that magnolol and 9-β-xylopyranosyl-isolariciresinol were the most active against the hepatitis B virus. [Display omitted] ► The constituents of stem bark of Streblus asper were investigated. ► Activity-guided isolation led to discovery of 22 compounds including 7 previously unreported. ► 10 compounds exhibited anti-HBV activities in vitro. ► Magnolol and 9-β-xylopyranosyl-isolariciresinol showed significant anti-HBV activities. Seven compounds, (7′S,8′S)-trans-streblusol A, (7′R,8′S)-erythro-streblusol B, (7′S,8′S)-threo-streblusol B, 8′R-streblusol C, streblusquinone, (8R,8′R)-streblusol D, and streblusol E, along with 15 known compounds (8–22) were isolated from the n-butanol-soluble part of the MeOH extract of stem bark of Streblus asper. Their structures were elucidated through application of extensive spectroscopic methods, including ESI-MS and 2D NMR spectroscopy (HMQC and HMBC). 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 and allylbenzene derivatives were evaluated for their anti-HBV activities in vitro using the HBV transfected Hep G2.2.15 cell line. The most active compounds, magnolol and 9-β-xylopyranosyl-isolariciresinol, exhibited significant anti-HBV activities with IC50 values of 2.03 and 6.58μM for secretion of HBsAg, with no cytotoxicity, and of 3.76 and 24.86μM for secretion of HBeAg, with no cytotoxicity.