Investigation for antidiabetic agonist from Wisteria floribunda seeds.

Abstract

Peroxisome proliferator-activated receptor γ (PPAR γ) is a ligand-dependent transcription factor that directly activates the expression of adipocyte-specific genes. PPAR γ is mainly distributed in adipose tissues, and regulates lipid and glucose metabolism. Thiazolidinediones (TZDs), as synthetic PPAR γ ligands and antidiabetic drugs, are able to stimulate adipogenesis and enhance insulin sensitivity by stimulating the transcriptional activity of PPAR γ. Through screening for natural PPAR γ activator in various plant seeds using the PPAR γ luciferase reporter assay, the methanol extracts of Wisteria floribunda seeds activated PPAR γ. To identify the active compound that activated PPAR γ, the methanol extracts of Wisteria floribunda seeds was partitioned between hexane, ethyl acetate and H₂O soluble fractions. Among these, treatment with the ethyl acetate extracts of Wisteria floribunda seeds enhanced a marker of adipocyte differentiation such as triglyceride accumulation in 3T3-L1 cells. These results suggest that Wisteria floribunda seeds possess PPAR γ activators. The ethyl acetate soluble fraction of Wisteria floribunda seeds was further separated by silica gel and ODS column chromatography. Based on NMR, ESI-MS, and luciferase reporter assay, we confirmed that blumenol A, wistin, and isomucronuratol were identified as PPAR γ activators in Wisteria floribunda seeds.