Phenolics with PPAR-γ ligand-Binding activity obtained from licorice (Glycyrrhiza uralensis Roots) and ameliorative effects of glycyrin on genetically diabetic KK-Ay mice

The EtOAc extract of licorice (Glycyrrhiza uralensis roots) exhibited considerable PPAR-γ ligand-binding activity. Bioassay-guided fractionation of the extract using a GAL-4-PPAR-γ chimera assay method resulted in the isolation of two isoflavenes, one of which is a new compound named dehydroglyasperin D, an isoflavan, two 3-arylcoumarins, and an isoflavanone as the PPAR-γ ligand-binding active ingredients of licorice. The isoprenyl group at C-6 and the C-2′ hydroxyl group in the aromatic ring-C part in the isoflavan, isoflavene, or arylcoumarin skeleton were found to be the structural requirements for PPAR-γ ligand-binding activity. Glycyrin, one of the main PPAR-γ ligands of licorice, significantly decreased the blood glucose levels of genetically diabetic KK-Ay mice.