Dual high-resolution profiling integrates α-glucosidase inhibition and DPPH assays to identify bioactive constituents in Lygodium japonicum roots.

This study aimed to isolate and characterize α-glucosidase inhibitory and antioxidant compounds from the roots of Lygodium japonicum and to investigate their interactions with α-glucosidase. Dual high-resolution α-glucosidase inhibition and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging profiling was employed, which led to the identification of 12 constituents associated with α-glucosidase inhibitory and/or antioxidant activities from L. japonicum roots, including two new compounds, 6-hydroxy-7-(hydroxymethyl)-2-isopropyl-1,4-naphthoquinone (7) and 1,1'-dimer of 2,3-dihydroxy-4-methoxydibenzofuran (10). Several isolated compounds showed notable bioactivities, with compounds 7, 8, and 10 exhibiting measurable α-glucosidase inhibitory activity (IC50 < 11 μM) and compounds 1, 2, 4, 5/6, and 10 displaying robust DPPH radical scavenging activity (IC50 < 20 μM). Enzyme inhibition kinetics, fluorescence spectroscopy, circular dichroism spectroscopy, and molecular docking were employed to characterize three of the most potent α-glucosidase inhibitors and to reveal their potential binding interactions with the enzyme. Overall, this study highlights the utility of dual high-resolution bioactivity profiling for identifying chemically defined constituents that contribute to the in vitro α-glucosidase inhibitory and antioxidant activities of L. japonicum roots.