Lignans from the heartwood of Streblus asper and their inhibiting activities to Hepatitis B virus

Three new lignans, erythro-strebluslignanol (1), threo-7′-methoxyl strebluslignanol (2) and erythro-7′-methoxyl strebluslignanol (3), together with twelve known compounds were isolated from the n-butanol and chloroform fractions of the heartwood of Streblus asper. Their structures were elucidated through extensive spectroscopic methods, including MS and 2D NMR experiments (HMQC and HMBC). The stereochemistry at the chiral center was determined using CD spectra, as well as analysis of coupling constants and optical rotation data, respectively. Primary bioassays showed that 6-hydroxyl-7-methoxyl-coumarin (5) and ursolic acid (10) showed anti-HBV activities, with IC50 values of 29.60 μM and 89.91 μM for HBsAg at no cytotoxicity, and IC50 values of 46.41 μM and 97.61 μM for HBeAg at no cytotoxicity, respectively.

Graphical abstractStructures and absolute stereochemistry of three new lignans (1–3) isolated from the n-butanol fraction of the heartwood of Streblus asper have been determined by detailed spectroscopic analyses. Anti-HBV activity assay of the isolated compounds indicated that 6-hydroxyl-7-methoxyl-coumarin and ursolic acid showed moderate activity against Hepatitis B virus.Figure optionsDownload full-size imageDownload as PowerPoint slide