Lignans from the Roots of Taxus wallichiana and Their α-Glucosidase Inhibitory Activities

From an EtOAc-soluble extract of the roots of Taxus wallichiana, six new (16) and 11 known lignans were isolated. The structures of the new compounds were elucidated based on interpretation of spectroscopic data. (+)-7'-epi-Tsugacetal (1) is a rare aryltetralin-type lignan having a cis-orientation of H-7' and H-8'. Compounds 36 were identified as the first naturally occurring tetrahydrofuranoid lignans having a cis-orientation of H-7 and H-8. All tested compounds were found to possess alpha-glucosidase inhibitory activity, with formosanol (9) showing the most potent effect with an IC50 value of 35.3 mu M.