Homoisoflavonoids from the Fibrous Roots of <i>Polygonatum odoratum</i> with Glucose Uptake-Stimulatory Activity in 3T3-L1 Adipocytes

The EtOAc-soluble fraction of a 90% MeOH extract of the fibrous roots of <i>Polygonatum odoratum</i> was found to potentiate insulin-stimulated glucose uptake in differentiated 3T3-L1 adipocytes. Bioassay-guided fractionation yielded nine homoisoflavonoids (<b>1</b>−<b>9</b>), four of which were new (<b>1</b>−<b>4</b>), together with an isoflavone glycoside (<b>10</b>) and a flavanone glycoside (<b>11</b>). The structures of new compounds were elucidated on the basis of extensive 1D and 2D NMR spectroscopy, and the absolute configurations were deduced by CD spectra. All 11 compounds showed effects of sensitizing adipocytes for insulin in a cell-based glucose uptake assay using 3T3-L1 adipocytes. The results indicate that homoisoflavonoids may be potential insulin sensitizers.