Anthocyanin Metabolomic Analysis and Inhibitory Effect on Digestive Enzyme of Phenolics from Allium mongolicum Regel Flowers.

A. mongolicum flowers from three origins were analyzed for anthocyanin and flavonoid composition and inhibitory effect on α-glucosidase and pancreatic lipase. Metabolomic analysis revealed that a total of 69 anthocyanin and flavonoid compounds were detected in A. mongolicum flowers, among which quercetin-3-O-glucoside (Q3G) and cyanidin-3-O-(6-O-malonyl-β-D-glucoside) (C3MG) were predominant. The IC₅₀ values for α-glucosidase and pancreatic lipase inhibition of A. mongolicum flower phenolics from three origins ranged from 0.13 to 0.20 and 0.10 to 0.15 mg/mL, respectively, and the phenolics inhibited α-glucosidase and pancreatic lipase in a reversible mixed noncompetitive manner. A. mongolicum flower phenolics bind to the enzyme through multiple sites (n > 1), altering the microenvironment of aromatic amino acid residues in the enzyme and inducing conformational changes. The interaction between A. mongolicum flower phenolics and α-glucosidase was dominated by hydrophobic interactions (ΔH and ΔS were both positive), while the interaction between phenolics and pancreatic lipase primarily involved van der Waals forces and hydrogen bonds (ΔH and ΔS were both negative). Fourier Transform Infrared Spectroscopy (FTIR) revealed that phenolics interacted with α-glucosidase/pancreatic lipase via non-covalent bonds. Scanning electron microscopy showed that phenolics from A. mongolicum flowers changed the morphological features of the enzyme surfaces. Molecular docking revealed that the phenolic compounds bind spontaneously to the α-glucosidase and pancreatic lipase with binding energies ranging from - 9.8 to -7.7 kcal/mol, demonstrating strong binding affinity. Overall, A. mongolicum flowers have the potential to serve as functional foods or nutraceuticals for the preventing and treating of obesity and diabetes.