DPP-IV Inhibitory Potentials of Flavonol Glycosides Isolated from the Seeds of : In Vitro and Analyses.

Dipeptidyl peptidase IV (DPP-IV), a new target for the treatment of type 2 diabetes mellitus, degrades incretins such as glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide. DPP-IV inhibitors shorten the inactivation of GLP-1, permitting the incretin to stimulate insulin release, thereby combating hyperglycemia. In our ongoing search for new DPP-IV inhibitors from medicinal plants and foods, three flavonol glycosides (⁻) were isolated from the seeds of Medikus (Fabaceae) and tested for their DPP-IV⁻inhibitory activity. We demonstrated for the first time, that compounds ⁻ inhibited DPP-IV activity in a concentration-dependent manner in our in vitro bioassay system. In addition, molecular docking experiments of compounds ⁻ within the binding pocket of DPP-IV were conducted. All investigated compounds readily fit within the active sites of DPP-IV, in low-energy conformations characterized by the flavone core structure having optimal electrostatic attractive interactions with the catalytic triad residues of DPP-IV.