Potent alpha-glucosidase inhibitors from the roots of Panax japonicus C. A. Meyer var. major.

Bioassay-guided fractionation of the CHCl(3) soluble portion of the roots of Panax japonicus C. A. Meyer var. major afforded an active fraction with inhibitory activity against baker's yeast alpha-glucosidase with an IC(50) value 1.02 mg/mL. Furthermore, the active fraction isolated contained three previously unreported polyacetylenes, designated panaxjapynes A-C, together with 11 other compounds, including four polyacetylenes, five phenolic compounds, a sesquiterpenoid, and a sterol glucoside. The structures of the compounds were elucidated by spectroscopic and chemical methods. Compared with the control acarbose (IC(50) 677.97 microM), six compounds were shown to be more potent alpha-glucosidase inhibitors with IC(50) values in the range 22.21-217.68 microM.