Identification of Potential α-Glucosidase Inhibitors from American Ginseng Processed Products by UHPLC-Q-Orbitrap/MS and Molecular Docking

Abstract

The traditional herb American ginseng (Panax quinquefolium L.) can be processed into two common products: dried American ginseng (DAG) and red American ginseng (RAG), which have well-established hypoglycemic activity, making it a functional food as well. However, the mechanism by which the main active ingredients inhibit α-glucosidase, a crucial target for hypoglycemic drugs, remains unclear. In this research, we employed ultra-high-performance liquid chromatography coupled with quadrupole orbitrap mass spectrometry (UHPLC-Q-Orbitrap/MS) to analyze the chemical composition of ethanol extracts of dried American ginseng (EDAG) and red American ginseng (ERAG). Subsequent in vitro experiments were conducted to assess the α-glucosidase inhibitory activity of EDAG and ERAG. Comparative enzymatic kinetics analyses were performed as well. Molecular docking analysis revealed the interaction between the differential saponins and α-glucosidase, further validated through verification experiments. Among the total 47 identified saponins, 9 were characterized by OPLS-DA as differentially expressed between EDAG and ERAG. Notably, ERAG exhibited more robust α-glucosidase inhibitory activity than EDAG. Enzyme inhibition kinetics revealed that both products displayed reversible mixed-type inhibition on α-glucosidase, suggesting their inhibitory effects are associated with saponin composition. Molecular docking studies demonstrated that all 9 differential saponins exhibited inhibitory effects on α-glucosidase. Verification studies substantiated ginsenosides like Rb₁, Rd, and others as inhibitors of α-glucosidase. These findings contribute to a more comprehensive understanding of processed American ginseng and provide valuable insights for developing glucose-lowering functional foods.