Potential anti-diabetic components of Apocynum venetum L. flowers: Optimization, chemical characterization and quality evaluation

Apocynum venetum L. flowers are the source of beverage and primary nectar with potential industrial value but have received less attention. This study aimed to investigate its processing, chemical characterization and quality evaluation of the potential antidiabetic activity. Compared with heat reflux extraction, the ultrasound-assisted extraction (UAE) method had the advantages of low cost and high bioactivity. The UAE method was optimized by response surface methodology based on potential antidiabetic activity. The optimal conditions were 40% ethanol, 77 °C, 47 min, and 1:23 g/mL; and the active components were enriched by macroporous resin HPD-600 with great α-glucosidase inhibition (IC50 = 4.65 ± 0.14 μg/mL). Furthermore, the fingerprint-effect relationship was analyzed using grey relational analysis (GRA) and orthogonal partial least squares regression (OPLS), and chemical composition were identified using UHPLC-Q-Orbitrap-HRMS. The first two effective compounds, hyperoside and astragalin, contributed significantly to α-glucosidase inhibition, and their content was 15.3 ± 0.2 mg/g and 66.6 ± 1.3 mg/g using the HPLC method we established; they bind with the active pocket of the human α-glucosidase enzyme, mainly depended on the hydrogen bonding, hydrophobic bonding and Pi-Pi stacking. In addition, according to the retention time, mass data, standards and references, thirty compounds were identified, which have potential antidiabetic activities.