Potent sucrase inhibition by purple sweet potato anthocyanins for glycemic control: unveiling peonidin-3-caffeoyl-feruloylsophoroside-5-glucoside as the key functional monomer and its interaction mechanism.

Purple sweet potato anthocyanins (APSP) are promising natural sucrase-inhibitory agents for postprandial glycemic control; however, their key bioactive constituents and underlying mechanisms remain unclear. In this study, APSP was found to interact with sucrase (493.33 ± 29.02 nm), leading conformational changes through spontaneous binding. Peonidin-3-caffeoyl-feruloylsophoroside-5-glucoside (P-3-C-FS-5-G) was identified and isolated (purity ≥90.5%) as the major sucrase-inhibitory monomer from APSP. P-3-C-FS-5-G produced dose-dependent competitive inhibition (inhibition rate 24.11 ± 3.05%). It improved glucose uptake in insulin-resistant HepG2 cells (158% of the model group). Molecular docking and molecular dynamics simulations demonstrated the stable accommodation of P-3-C-FS-5-G within the sucrase active site (Ser121, Gln239, Asp275) via hydrogen bonding, electrostatic interactions, and van der Waals forces. Sucrase retarded the degradation of P-3-C-FS-5-G, suggesting improved structural stability. These findings identify P-3-C-FS-5-G as a dominant functional constituent of APSP and provide mechanistic insight to support the development of APSP-based functional foods for glycemic regulation.