α-Glucosidase Inhibitors from Marrubium astracanicum: Isolation and Molecular Docking

Marrubium astracanicum Jacq., Lamiaceae, is an herbaceous plant distributed in Iran, Turkey, and southern Caucasia. In the present study, α-glucosidase inhibitory principles of M. astracanicum aerial parts were investigated by a bioassay-guided approach. The extraction procedure from the plant aerial parts was carried out successively using petroleum ether, ethyl acetate, and methanol. The ethyl acetate extract, with the highest in vitro α-glucosidase inhibitory activity, was subjected to further chemical investigation. The structures of the isolated compounds were elucidated by 1 H-NMR and 13 C-NMR spectral analyses as apigenin-7- O -(3′′-( E ) -p -coumaroyl)-β- d -glucoside, apigenin-7- O -(6′′-( E )- p -coumaroyl)-β- d -glucoside, martynoside, apigenin-7- O -β- d -glucoside, and verbascoside. In addition, the antidiabetic potential of the isolated compounds was evaluated in an in vitro α-glucosidase inhibitory assay, and kinetic and molecular docking studies were done for the most active compound. Apigenin-7- O -(3′′-( E ) -p -coumaroyl)-β- d -glucoside and apigenin-7- O -(6′′-( E )- p -coumaroyl)-β- d -glucoside showed the most potent in vitro α-glucosidase inhibitory activity with IC 50 values of 57.4 ± 1.2 and 186.4 ± 2.5 μM, respectively, which was about 4 to 13 times lower than the IC 50 value of the reference compound acarbose (751.2 ± 0.4 μM). Graphical abstract