Rapid screening of potential α-glucosidase inhibitors from the waste leaves of Rheum tanguticum by activity-oriented extraction and enrichment optimization, UPLC-QTOF-MS/MS, molecular docking and in vitro validation

In the present study, an efficient strategy has been established for rapid screening of potential α-glucosidase inhibitors from the waste leaves of Rheum tanguticum by activity-oriented extraction and enrichment optimization, UPLC-QTOF-MS/MS, molecular docking, and in vitro validation. With α-glucosidase inhibitory activity as the evaluation index, the extraction process was optimized by response surface methodology and the enrichment process by macroporous resins was optimized by adsorption and desorption experiments. The active flavonoids yield was 8.85 mg/g under the optimized extraction conditions. After AB-8 macroporous resins enrichment, the active flavonoids purity increased from 2.89 % to 47.6 %, a 17-fold increase, while the IC50 of α-glucosidase reduced from 13.97 mg/mL to 412 μg/mL, a 33.9-fold reduction. Thirty-six flavonoids in the active flavonoids fraction were identified by UPLC-QTOF-MS/MS. Molecular docking screening, in vitro activity assay and multispectral approaches verification confirmed the potential of six flavonoids as novel α-glucosidase inhibitors.