Magnetic beads-based ligand fishing for rapid screening of dietary α-glucosidase inhibitory ligands from the rhizome of Alpinia officinarum Hance combined with molecular docking

BACKGROUND The rhizome of Alpinia officinarum Hance, considered as a medicinal and edible plant, is gathering increasing attention as a natural source for exploring dietary α-glucosidase inhibitors. Magnetic beads-based ligand fishing has shown great promise for accelerating identification of bioactive constituents from complex plant extracts. However, immobilization efficiency and stability when using different aldehyde-activated magnetic beads is still unclear. Moreover, non-specific binding hampers characterization of inhibitory ligands. RESULTS Immobilized enzymes on 3-carbon linker length (AG NTC - 3 MB) and 21-carbon linker length (AG NTC - 21 MB) supports were synthesized, respectively. The highest immobilization efficiency of 91.13 ± 0.40% was observed when the mass ratio of MBs-C21 to α-glucosidase was 10:1. The catalytic activity of AG NTC - 21 MB was four- to eight-fold higher than that of AG NTC - 3 MB. Additionally, after 56 days, the catalytic activity of AG NTC - 21 MB retained 73.4–90.3% activity – more stable than AG NTC - 3 MB (18.2–32.2%). In a proof-of-concept study, AG NTC - 21 MB-based ligand fishing led to the identification of 12 ligands. Among them, two flavonoids – kaempferol ( 1 ), galangin ( 6 ) – and three diarylheptanoids – 7-(4-hydroxyphenyl)-1-phenyl-4-hepten-3-one ( 9 ), 7-(4-hydroxy-3-methoxyphenyl)-1-henylhept-4-en-3-one ( 11 ), and 1,7-diphenyl-4-hepten-3-one ( 15 ) – exhibited significant α-glucosidase inhibitory activity, with IC 50 values in the range of 23.6 ± 0.7 to 146.2 ± 3.8 μmol L −1 , and showing a mixed-type behavior with K i values ranging from 42.6 ± 2.0 to 786.0 ± 13.9 μmol L −1 . Molecular docking showed compounds 6 , 9 , 11 , and 15 bind with α-glucosidase by H-bonds, electrostatic and hydrophobic interactions. CONCLUSION Aldehyde-activated magnetic beads with 21-carbon linker length and AG NTC - 21 MB are superior to AG NTC - 3 MB in terms of immobilized efficiency, enzymatic activity, and stability. AG NTC - 21 MB-based ligand fishing combined with high-performance liquid chromatography–quadrupole time-of-flight–mass spectrometry and molecular docking constitute an effective and robust bioanalytical technology platform for analyzing antidiabetic composition in A . officinarum . Flavonoids and diarylheptanoids are responsible for the α-glucosidase inhibitory effect of the methanolic A . officinarum extract. The pharmacological and chemical profiles support further research with the aim of developing A. officinarum into functional food for prevention and management of type 2 diabetes and related complications. © 2025 Society of Chemical Industry.