Interactions between Phenols and Alkylamides of Sichuan Pepper (<i>Zanthoxylum</i> Genus) in α-Glucosidase Inhibition: A Structural Mechanism Analysis

The phenols and alkylamides in 26 varieties of <i>Zanthoxylum</i> pericarps (ZP) were comparatively identified, and the contribution of these key components to the inhibition of <i>in vitro</i> α-glucosidase (α-Glu) was confirmed using principal component analysis (PCA) and ingredient recombination models. Additionally, spectrophotometric assays, nuclear magnetic resonance (NMR), and molecular docking (MD) were employed to characterize the interactions among key components in ZP when exposed to α-Glu. Four phenols and hydroxy-α-sanshool (α-SOH), which were recognized as main ingredients, presented an antagonistic effect in the inhibition of α-Glu. ¹H NMR demonstrated chemical shifts of certain hydrogens in the B phenolic ring and tetraenyl group, indicating a possible p-π conjugation between phenols and α-SOH. In addition, using MD analysis, the phenol-binding sites were observed to be negatively affected when α-SOH initially interacted with α-Glu. The combined results of the NMR and MD clarified the structural mechanism behind phenol/α-SOH antagonistic behavior in α-Glu inhibition.