Potent α-Glucosidase Inhibitors from the Roots of Aruncus sylvester

Two new acyl glucoses, 1,3,6-tri-O-(E)-caffeoyl-β-D-glucopyranoside (1) and 3,4-di-O-(E)-caffeoyl-α/β-D-glucopyranose (2), along with four known ones (3–6), were isolated from the roots of Aruncus sylvester. Their structures were elucidated on the basis of NMR spectroscopic analysis. Compounds 1 and 3 showed potent α-glucosidase inhibitory activity with IC50 values of 1.16 μM and 0.71 μM, respectively.