Mechanism studies on α-glucosidase inhibition and glycemic regulation of inotodiol from Inonotus obliquus.

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Citation abstract

Inonotus obliquus is a medicinal fungus that has been valued for its anti-diabetic properties in China for thousands of years. Inotodiol is a characteristic triterpenoid isolated from Inonotus obliquus. The inactivation effect and mechanism of α-glucosidase induced by inotodiol were investigated using fluorescence, FTIR, CD spectroscopy, and molecular dynamics simulation, and the glycemic regulation of inotodiol was studied on insulin-resistant HepG2 cells. Inotodiol could effectively inhibit α-glucosidase activity (IC 50 = 1.09 ± 0.08 mmol L -1 ) in a reversible and noncompetitive manner. Inotodiol interacted with α-glucosidase via a static quenching process with a binding constant of 1.52 × 10 3 mol L -1 at 298 K. Molecular dynamics simulation revealed that inotodiol interacted with α-glucosidase mainly by hydrogen bonding, and the complex system was stable. Furthermore, inotodiol could increase glucose consumption and glycogen synthesis in insulin-resistant HepG2 cells through the IRS1/PI3K/Akt-mediated GSK3β signaling pathway. Overall, this study suggested that inotodiol has the potential to be an agent or functional food for diabetics.