Computational stereochemical assignment of two new diastereoisomeric tetrahydrofuranoid-lignans from the roots of <i>Taxus wallichiana</i> (Taxaceae)

Two new diastereoisomeric tetrahydrofuranoid-lignans (<b>1</b> and <b>2</b>) were purified from <i>Taxus wallichiana</i> (Taxaceae) roots. Their respective structures were subsequently determined through spectroscopic analysis, together with GIAO NMR chemical shift calculation and DP4+ probability method to assign the relative configurations. A respective assignment of 7 <i>R</i>,8<i>R</i>,7′<i>R</i>,8′<i>R</i> and 7 <i>R</i>,8<i>R</i>,7′<i>S</i>,8′<i>R</i> was given for their absolute configurations, based on a comparative analysis between measured and calculated ECD data. Compounds <b>1</b> and <b>2</b> were examined for their <i>α</i>-glucosidase inhibitory effect, and their corresponding IC₅₀ values were 57.2 and 185.6 <i>μ</i>M, respectively, indicating greater potency than acarbose the positive control with IC₅₀ = 214.5 <i>μ</i>M.