Screening, characterization of trace α-glucosidase inhibitors from the root of Pueraria lobata and evaluation of their hypoglycemic activity

Pueraria lobata (Willd.) Ohwi (Gegen) is a nutritious medicine food homology plant that has been recorded in many ancient remedies for diabetes. However, its hypoglycemic active components and related mechanisms have not been fully elucidated. In this study, potential α-glucosidase inhibitors in Pueraria lobata were investigated by liquid-liquid refined extraction, high-resolution profiling and their hypoglycemic activity were evaluated. Ten compounds showing α-glucosidase inhibitory bioactivity were separated and identified, including two new compounds, 8-geranyl-7, 3′, 4′-trihydroxy-isoflavone (4) and 8-geranyl-7, 2′, 4′-trihydroxy-isoflavone (6), and eight known compounds. All screened compounds showed potential hypoglycemic activity, in which compounds 4, 6, 7, 8, 9 and 10 showed strong inhibitory activity (IC50 < 8 μM). Furthermore, molecular docking simulation revealed binding energy and interacting amino acid residues of the screened compounds with α-glucosidase, strongly supporting their potential as α-glucosidase inhibitors.