4-O-Mono-Fructosyl Phlorizin-Enriched Fraction and Its Interaction with Carbohydrate Digestive Enzymes: In Vitro and In Silico Studies

Diabetes mellitus represents a major global health challenge, which has generated ongoing interest in developing enzymatic strategies to modulate carbohydrate digestion. Phlorizin, a dihydrochalcone found predominantly in plants of the genus Malus, has been extensively investigated for its antidiabetic potential; however, its practical application is limited by its low water solubility. Enzymatic fructosylation represents an effective biocatalytic approach to overcome this limitation and modulate the functional properties of phenolic compounds. In this study, the inhibitory activity of an enzymatically fructosylated phlorizin-enriched fraction, containing 4-O-mono-fructosyl phlorizin (4PHF) as its main component, was evaluated against key carbohydrate-digesting enzymes using in vitro assays complemented by in silico molecular docking analyses. The 4PHF-enriched fraction showed potent inhibition of α-amylase in vitro, with an IC50 value of 2.69 µg/mL. However, no significant inhibition of α-glucosidase was observed within the analyzed concentration range, indicating a selective inhibitory profile. Molecular docking analyses supported the experimental findings, revealing favorable binding orientations and predicted affinities of 4PHF for α-amylase and α-glucosidase, stabilized primarily by hydrogen bond interactions. Overall, the combined in vitro and in silico results demonstrate that enzymatic fructosylation effectively reprograms the enzyme interaction profile of phlorizin, highlighting 4PHF as a structurally optimized modulator of carbohydrate-digesting enzymes, with potential relevance for applied research on enzyme inhibition related to metabolic diseases.